Shop Efficiency Part 7 - CNC Programming

Our Shop Efficiency series has really taken off ... and we would like to take a few lines to say Thank You to all our readers for your email comments and support. We are very pleased that we have been able to take some of our real world machining and machine shop experiences and turn them into valuable tips and pointers and pass them on to so many of you. Thanks so much for your support.

First - A little background on this Post
At first glance ... since Kentech Inc. develops and sells CNC programming software ... this post might look like straight marketing and a sales pitch for our Kipware® conversational CNC programming software. Actually ... it's a story of just the opposite. Most of our software titles have been designed and developed based on what we saw was lacking in our many years on the shop floor. Our Kipware® conversational CNC programming software is a product of that experience.

One of my most telling personal experiences was working in a shop here in Masachusetts as a CNC machinist. The shop was your typical job shop with all kinds of work coming through the door. Most of it was fairly simple ... with a few plastic injection mold type jobs every once in a while. The CNC programming was supposed to be done by the shop floor machinists ... using a CAM plug-in for Solidworks ... which was a bit complex. No CAD/CAM training more than a simple tutorial was offered or provided. As a result ... since most shop floor machinists were great at cutting chips but lacked intense CAD/CAM experience ... and the jobs were fairly simple ... they often resorted to manual programming. The result was programs loaded with mistakes ... from typo-errors to incorrect toolpaths ... and the result from that was scrap, broken tools and sometimes worse ... but the overall effect was complete shop floor inefficiency.

The frustration level on the floor ... needless to say ... was very high. The machinists were basically unable to do their job ... because no one trained them on the complex CAD/CAM system ... and there were no other tools to help them ... other than an editor.

In this environment ... our conversational CNC programming concept and design was born. It was plain to see that the CAD/CAM and a CAD/CAM programmer was required for the mold work ... but clearly for the 95% of programming we did on the shop floor it was NOT required. In fact ... having the CAD/CAM option as the only option ... actually made things worse.

CNC Programming and the LINK to Shop Efficiency
Which brings us to this post and the subject of CNC programming as it pertains to shop efficiency. Obviously ... if the program isn't created in an efficient and correct manner ... the parts don't get made and the money doesn't flow. But just as important as tooling and fixturing ... the program creation process must have options also. You wouldn't think of placing a simple rectangular piece of stock in a custom made fixture ... you would use a vise. In the same way ... you shouldn't think of programming a simple part with a round pocket and bolt circle through a complex CAD/CAM system. The real key to efficient shop floor programming is having an ARSENAL of tools at your disposal. Thinking about your CNC programming as more of a tool ... with multiple choices for various situations ... will help your shop floor reach a higher level of efficiency.

CNC Programming Tools Available
We've listed what we consider to be the realistic options for CNC programming available to anyone creating CNC programs in a "job shop" environment ... the environment where our readers predominately are working ... and the options up for discussion in this post.

1. CAD/CAM
2. Off-Line Conversational CNC Programming Software
3. Conversational CNC Controls
4. G Code "wizards"
5. Manual Programming through an Editor

"Wizards" and Manual Programming
To narrow the discussion a bit ... let's remove the two options that are really not realistic in a professional machine shop environment. So called G code wizards are way too simplistic and act

more as hindrance and weight than any kind of efficient tool. Full conversational programming software makes much more sense both from a financial and capabilities perspective. Full, quality conversational software is a programming system ... not a simplistic crutch.

Manual G code programming should only be considered for the simplest of parts. Human error plays too great of a role in any other scenario and really renders this option a last resort choice for a professional programming environment.

That's not to minimize manual CNC programming knowledge and experience. Any CNC programming option used is made VASTLY more efficient and productive when operated through the hands of an experienced manual CNC programmer. A good Editor should always be available to allow that experienced CNC programmer the tool to alter or edit auto-created G code. The point here is that creating programs from scratch manually is not a good choice. Even for simpler programming ... a tool that will auto-generate the code provides stability ... and the manual tweaking of the code can enhance that output greatly.

CONVERSATIONAL and CAD/CAM
Efficient CNC Programming Requires an ARSENAL of Tools
It's more about OPTIONS than OPTION
In a professional environment ... really the two main options are CAD and / or CAM and full, quality conversational programming software. The CAD/CAM option can really be broken down into two options. First the CAD option is a must for any design environment ... even when that is just supporting the shop floor with fixture design. Professional CAD can range from the simple to the complex ... and from the FREE to megabucks. Each shops design and CAD needs would drive that discussion. However ... going from the CAD drawing to a G code program does not necessarily have to through the expensive and complete CAD/CAM system.

Using conversational software ... that CAD drawing can also be turned into a G code program. DXF import can be used in quality conversational software and a variety of other applications to go from a CAD drawing to a G code program.  And of course ... the integrated CAM option can be used to go from that CAD drawing to a G code program.

The main point is that no two workpieces are exactly alike ... and the right programming option for one will most likely not be the right programming option for another. From our experiences ... the best programming method for any job involves (2) main factors :

• Who is the best choice to create that program? Shop floor? Dedicated programmer?
• What is the best tool for that individual to use to create that program quickly and accurately?

Letting the correct answers to these questions guide the process ... rather than forcing the path because of limited options ... will increase your shop efficiency when it comes to programming your CNC's. Some thoughts :

• Maybe the best person to create the program is not full CAD/CAM proficient but would be the best chip-maker for the job ... a shop floor conversational programming option might be the best solution. 
• Perhaps the job is very complex ... and the only solution for an accurate and efficient toolpath is the CAD/CAM alternative. 

The point to make is that with an arsenal of tools available ... the experience of your personnel and the complexity of the workpiece / programming can dictate the most efficient path to take for the program creation. This allows for the free flow of efficiency ... rather than ramming the square process through a round hole.

Machine Tools with conversational CNC controls
Conversational CNC controls mounted directly to a CNC machine appear to be the perfect solution ... but actually have some important points to consider. The alternative of purchasing a laptop or Windows based tablet ... loading it with conversational software ... is more often than not the better alternative. Here are our major reasons to support this claim :

1. CHEAPER ... conversational CNC controls can be quite expensive. A tablet with conversational software will cost less than $1200.
2. PORTABILITY ... having the ability to do the programming on the shop floor, in the office, at home ... makes a portable alternative very attractive.
3. PROGRAM MULTIPLE MACHINES ... the ability to simply move the laptop around or pass it off to someone else gives you the ability to use the "conversational control" on multiple machines. Other machines can also be purchased without the conversational option ... you already have a "conversational control".
4. PROGRAMMING AT THE MACHINE ... even though most modern conversational controls have basically (2) modes ... the conversational programming mode and the machine operation mode ... they can often result in headaches and frustration. Either the machine is not runnning waiting for a program to be created ... or the machinist is programming the next job while trying to run production. Not the best environment to say the least.
5. CNC CONTROLS ARE NOT COMPUTERS ... most industrial grade CNC controls do not have the power or capability of a desktop or laptop PC ... they are simply not constructed from the same components. And if they are a PC ... they are most likely NOT an industrial grade PC and not fit for the harsh machine shop environment.
6. CONVERSATIONAL SOFTWARE IS MORE POWERFUL ... backed by the power and capabilities of a PC ... conversational SOFTWARE is more powerful and has more options than conversational software operating on a CNC control.

Some Closing Thoughts ... 
The main reason for combining this post into our Shop Efficiency series is to get shops thinking about all the potential programming tools available. Our experience shows that the most efficient CNC programming is accomplished when an ARSENAL of good tools are made available. Inevitably users might find and use their favorite tools ... but the key is that they have the ability to choose from an assortment. Also ... that the other tools remain available when the need arises ... providing choices. Also ... when an assortment of tools is available ... shops can increase the number of people who can create those programs ... and that is a huge jump in shop efficiency. Creating CNC programs faster ... using more people ... means more spindles turning and that means more profits being generated. And isn't that the true test of Shop Efficiency?

Please come back for our next installment in our series on Shop Efficiency.

Until next time ... Happy Chip Making !!

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Shop Efficiency - Part 6 : Multi-Function Tools

Multi-function tools have been around for quite a while but oftentimes are overlooked for a variety of reasons ranging from lack of understanding to shop inventory. But the truth is that in many situations, multi-function tools can be a key to reduced cycletime ... more efficient machining ... better workflow ... and that ultimate prize ... increased shop efficiency.

In this installment of our Shop Efficiency Series ... will take a quick look at some of the more common multi-functions tools ... outline some of their features and benefits ... to hopefully bring about a better understanding and start that "machinist mind" thinking about how these types of tools might be able to benefit your particular shop efficiency.

Milling : Multi-Function End Mill
Multi-function end mills are designed with two main features ... low cutting resistance and good chip evacuation when center cutting / drilling and milling at an angle. These two features give these tools the ability to perform both drilling and milling ... which makes them an indispensable part of your tooling inventory. Imagine being able to select either plunge milling or side milling when machining ... or employing a combination of both because the tool has that capability. The image below gives the whole range of machining op's that are available with this tool type ... it illustrates well their flexibility and capability ... and speaks volumes about why they should be one of your go-to tools. As you can see there are a variety of operations where they can make an impact.

Additional Information / Recommendation :

Tool Name / Manufacturer : Kyocera MEY - Ultra Drill Mill

Catalog / Brochure Link : http://global.kyocera.com/prdct/tool/pdf/e-d_mey.pdf

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Milling : Thriller - Drill / C'Sink / Tap
If you have never utilized a combination drill / thread mill ... this tools will really blow your mind. Center drilling ... drilling ... countersinking ... thread milling or tapping as means of creating a tapped hole is SOOOO NOT KOOL !! 4 tools combined with the tool changes ... stopping and starting ... tool costs ... etc. ... make this method of creating threaded holes simply NOT ACCEPTABLE when discussing shop efficiency. You may have held off on these thinking that they are really for specific types of threaded holes ... but the more you look the more they make sense as the go-to-tool .. with tapping and other standard operations as the secondary option. Our favorite tool comes from Emuge Corp. ... which also has outstanding field support BTW ... and combines drilling, countersinking and thread milling in one tool ... quickly illustrated below.

But rather than yapping about all the benefits ...we suggest watching the video link below ... it tells the story way better than words.

Additional Information / Recommendation :

Tool Name / Manufacturer : Emuge Corporation - Thriller

Catalog / Brochure Link : http://emuge.com/media-resources/brochures-catalogs/4-fluted-solid-carbide-thrillers

Video Link : https://www.youtube.com/watch?v=OdOfHEzXMMA

Video Link : https://vimeo.com/6245960

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Turning : Groove / Turn Tools
For machining operations that include both turning and grooving ... it oftentimes makes sense to combine those operations with one tool. Of course the type of material and type of groove machining play an important role here ... but when possible, using a combination groove-turn tool can be very beneficial and efficient. Eliminating the tool change and related non-cutting time can improve cycletime ... but the flexibility of the tool opens up a wide variety of machining options as well ... beyond just grooving operations.

As the illustration above shows ... machining operations such as PARTING OFF ... GROOVING ... BACK TURNING ... and STANDARD TURNING are all possible with this tool type. 

Additional Information / Recommendation :

Tool Name / Manufacturer : ISCAR - Groove-Turn

Catalog / Brochure Link : http://www.iscar.com/eCatalog/Applications.aspx?mapp=TG

Video Link : https://www.youtube.com/watch?v=HXhEtc1zl4w

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Turning : Boring with an Indexable Drill
In certain non-turning tool applications ... it is possible to utilize the same indexable drill used to drill a hole as a boring bar to open up the hole diameter. Benefits of course include decreased cycletime and the use of less tools ... but this should be considered carefully and success involves many factors. As stated many times in our blog ... we recommend Sandvik tooling quite often ... and they have a great online resources that delves into this type of machining and the options to consider before giving it a go in the link below ... just click the image to open up their information page :

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Of course there are thousands of ways to use standard type tooling as a multi-function tool ... and we are sure that your machinist mind has come up with some novel ones along the way. But we felt the need to include at least some of the more "common" options in any conversation about shop efficiency. So there you have it. Some food for thought ... and some multi-function tooling options you may not have been aware of or considered.

Please come back for our next installment in our series on Shop Efficiency.

Until next time ... Happy Chip Making !!

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Shop Efficiency Part 5 : Re-Thinking Your Height Offset Strategy

As we have been stressing throughout this Shop Efficiency Series ... keeping your spindle running and the green cycle light lit is one of the main keys to making money and profits. In Part 5 we're going to shift our attention back to the VMC and HMC world and send out some thoughts regarding Tool Height Offsets ... "touching off" tools ... and how to get that inevitable task done quickly, easily and efficiently ... so that the spindle stays running and the tools gets in the chip.

Tool breakage or the need to replace dull or ineffective tools can cause huge loss of cutting times and spindle on time. With the implementation of the simple system we outline below ... you can insure that replacing or setting up your tools for machining can be done quickly and efficiently with as little disruption to cutting time as possible. There are some initial costs involved ... but the ROI is fast and you'll see the results immediately.

We'll take you through the Set-Up and Process first to show you how it works ... then highlight some of the Features and Benefits that can achieved by utilizing this system. The basic idea is to utilize a MASTER TOOL to set the part Z0 position ... and use the HEIGHT OFFSETS to calibrate the distance difference from the MASTER TOOL and EACH CUTTING TOOL. This system leaves us only the MASTER TOOL to re-calibrate for each workpiece ... and allows us to leave the cutting tools unchanged no matter what part we're running. Setting up ONE tool is obviously faster than setting up multiple tools.

What You'll Need :

1. Height Gauge ... digital gauge will obviously function the best.
2. Master Tool ( more details below )
3. Tool Holder Adapter or Setting Fixture

The Master Tool :
In order to utilize the features of this system, you'll need to create a MASTER TOOL. What we refer to as a master tool would be a piece of stock, say a piece of turned, ground and polished stock or drill rod loaded and secured into a tool holder. It should be secure in the holder ... the best way is with a shoulder butting against the tool holder face so it has a positive stop. Another feature is to make this master tool close to the length of the machine specs longest tool. This way you'll know that no cutting tool can be longer than this master tool.

Tool Holder Adapter or Setting Fixture :
Once you have created your stable Master Tool ... the next stable component should be your setting fixture. With a little thought and work you can turn a standard tool tightening fixture ... such as the ones pictured below ... into something suitable for this purpose ... with the main criteria being the stable repeatability of the tool holder positioning.

The Process :
On a surface plate, set up your height gauge and tool holder adapter to allow for the measuring of your tools. To measure a tool :

• Place the MASTER TOOL in the setting fixture and set zero at the top of the master tool.

• Place a cutting tool to be measured in the setting fixture and record the reading at the top of the tool's cutting edge. This is the distance from the master tool tip to the cutting tool tip. This dimension is the value that is to be entered in the machines height offset table for the measured tool.

• Repeat the second step above for each tool to be measured, recording the value on the height gauge for each tool.
• Load the tools in the magazine and enter the measured height offset values from Step #2 above into their respective height offset table positions.
• Using the MASTER TOOL, touch the Z0 surface of the workpiece and record the value from the home position to the Z0 location. This value should be entered in the Z table for the work offset (G54 - G59) to be used in the program.

That's it. 

Your program is ready to run. Your program will call up the G54 - G59 work offset or similar and will know the distance from the master tool to the Z0 location. Using the H value call in the program, the machine will calculate the difference between the master tool and the measured tool and adjust as required.

Now that we've set the thoughts and ideas in your mind ... feel free to deviate and expand on the basics outlined here.

Some Features and Benefits :

1. Let's suppose you're going to set up a new job next but will utilize some of the tooling from the previous job. The only set-up required is to use the Master Tool to touch the new Z0 surface, changing the value in the work offsets with this new value. Your cutting tools and their height offsets can remain the same. Save time by touching off one tool instead of many.
2. You can set-up a spare tool or replacement tool off the machine using the master tool and the height gauge ... insuring that your spindle will be back in the cut faster.
3. You can load say a nice cutting carbide mill in the magazine and use it for a variety of different jobs. No need to touch it off all the time, just use the master tool to get your work offset in Z.
4. Measuring tools becomes easier, allowing more people to assist with the tool setting . Setters don't need to know how to operate the machine.

From experience, once you try this method you'll find it saves you all kinds of time. The best advantage is being able to call out set tools that stay in the magazine. This really speeds up the set-up and changeover process.

Please come back for our next installment in our series on Shop Efficiency.

Until next time ... Happy Chip Making !!

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Shop Efficiency Part 4 : Re-Thinking Your Lathe Tooling

We've always been a big fan of Sandvik Coromant and their tooling ... not just because they are a member of the Kipware® family ... but we have always found their tooling, inserts, support and design to be cutting edge and of the best quality. On the shop floor ... they were our tooling manufacturer of choice and never let us down whether in standard type production or when we were looking for that new and innovative tool to get us through the toughest job or materials.

One of my personal best purchases was in converting our CNC lathe tool turret from standard lathe tooling to the Sandvik CAPTO system. I can compare this transformation to the points I outlined in Part #1 of this Shop Efficiency series ... click here to read that article ... and the transformation that takes place when you bring your VMC table into the 21st century. A CAPTO system will bring your CNC lathe turret into the 21st century.

First - What is CAPTO?
The CAPTO system is basically a quick-change, modular tooling system for CNC lathes and turning centers. Instead of mounting tooling directly into the turret ... tools are mounted to quick-change clamping units that are mounted onto the turret. Tools are then easily interchanged by simply changing the "head" mounted onto the clamping unit. Need to change from an 80 degree turning tool to a 55 degree ... just simple swap the "head". Need to change from a .750 insert drill to a 1.250 ... simply change the "head". For live tool turning centers ... need to change from a 1" drill to a face mill ... simply change the "head".

Second - Why Use CAPTO?
This type of modular tooling system comes with tons of advantages. Here are just a few of the more important ones pertaining to the Shop Efficiency factors which are the main focus of this series.

• Quick tool change which keeps the spindle running and the machine making chips / money. Not only in changing the complete tool type ... but insert changes can take place off-line while the head is replaced at the turret involving less time than an insert change.
• Greatly reduced set-up and changeover times because of the cutting edge repeatability when re-mounted in the clamping unit.
• Greater tool stability leads to improved cutting and cycletimes.
• Greater flexibility in tool selection and tool type.
• Same tooling can be used throughout the shop ... reduced tooling costs and inventory.
• Greater options for through-tool coolant delivery ... again, improved cutting and cycletimes.
• Turning Centers with Live Tools can see the biggest impact. By simply swapping heads that tool station can go from a face mill to a drill to an end mill in seconds. With greater repeatability meaning less set-up / touch off times. In addition ... turning that face mill station into a turning tool station can also be accomplished ... quickly and easily.

I could go on and on ... but I'm sure you're machinist mind sees the point.

Third - Cost vs Features
Like anything in life ... the system does require an initial investment. How much can be spread out over time as you integrate the system into the machine and the shop over time. I will say from

experience that the long term savings are there ... in quicker change overs, increased cycletimes and reduced tooling inventory ... especially if you integrate the system into multiple machines. The beauty part here is that once you have the clamping units on all your machines ... all machine will now utilize the same tooling. That is a huge advantage including reduced tooling costs and inventory all around.

RESULT - Increased Shop Efficiency
As you can see from the points outlined here ... there are a ton of features that can lead your CNC turning department to increased shop floor efficiency with the transformation through a CAPTO system. By integrating the system into your shop bit by bit you can defer the initial investment a bit and still reap the long term advantages and savings as you build the system into your shop floor. From faster insert changes ... to faster tool change-overs ... to faster set-up ... to improved cutting and cycletimes ... your shop floor can certainly reap improved shop efficiency with a CAPTO system.

LINKS for ADDITIONAL INFORMATION 

1. For a more in-depth look ... take a peek at the Sandvik Coromant video by CLICKING HERE.
2. For more information on CAPTO in general ... download the informational PDF by CLICKING HERE

Please come back for our next installment in our series on Shop Efficiency.

Until next time ... Happy Chip Making !!

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Shop Efficiency Part 2 : Face Drivers for CNC Turning

In our second installment in our series on Shop Efficiency we are about to take an in-depth look at a workholding option for CNC turning that very often goes unconsidered. "In the old days", turning between centers was the method of choice for any type of shaft or similar type workpieces. The process began with manually drilling center holes in each end of the material ... then attaching a drive dog on one end that was used to drive the parts rotation ... using the tailstock at the other end for support ... and the cutting began. With the advent of CNC ... turning between centers has for the most part become a lost and forgotten art. The use of soft jaws and the process of turning the part around has become the method of choice. Most machine tailstocks are pushed to the end limit and left there to collect chips or worse ... are not even considered or purchased when the machine is bought.

But with shops looking to increase production ... decrease set-up and set-up times ... and at the same time increase quality ... face drivers are getting a face-lift and are becoming more and more popular for many types of machining. The ability to machine the entire workpiece in one set-up gives shops the ability to maximize their production capabilities with only a minimal expense. So let's take a deeper look at face drivers ... the concept and the design.

Introduction to Face Drivers

As the above illustration shows ... the use of face drivers in conjunction with your CNC machine's tailstock ... allow complete access to the entire workpiece. This not only reduces the number of operations and set-up ... it greatly increases the accuracy of the workpiece machined. With everything machined in the same set-up ... tolerances and concentricity are greatly increased. Although most used for shaft work ... a quick look around the shop would probably reveal a lot of "shaft type" work where face drivers could be considered for the workholding option. Right and left hand turning can be employed as necessary without any restrictions.

How Does a Face Driver Work

The above illustration shows that the face driver consists of (2) main features ... the center and the drivers. The center fits into the spot drill or center drill hole that is pre-machined into the stock. The driver pins are what drives the workpiece in rotation and can either be hydraulic or mechanical ( such as spring loaded ). So as the workpiece is located between centers ... it is also pushed up against the drive pins which dig into the end of the workpiece and cause it to rotate as the spindle rotates.

Attaching the face driver to the spindle can be done with a variety of methods ... the easiest and most common is probably holding it in the chuck jaws. Depending on your spindle face and configuration ... other methods might be Morse Taper or a flange mounted directly to the spindle face.

The "clamping" of the workpiece is two fold ... centering followed by clamping. As the workpiece locates on the center points ... the action of the tailstock forces the workpiece onto the spindle side center and up against the drive pins. As the workpiece is forced deeper onto the center ... the drive pins dig into the face of the workpiece. The drive pins adjust individually to accommodate any irregularities in the face. Under the continued load of the tailstock, the drive pins penetrate and "clamp" the workpiece ... while the centers maintain the axis of rotation.

Points to Consider When Selecting A Face Driver

Here a couple of major points to consider when selecting a face driver ... these may also effect your decision to consider a face driver for your situation :

1. The diameter of the face driver ... as measured across the driver pins ... should be smaller that the diameter where it will be locating to allow for complete access to the workpiece material.
2. The diameter of the raw stock should not more than 3 times the diameter as measured across the driver pins.
3. Drive pins are different for CW and CCW rotation ... consider how you will be machining the workpiece and what direction the spindle will be rotating when selecting a face drive.

One of the top manufacturers of face drivers is Riten Industries Inc ... they can be found on the web along with additional information on face drivers and other CNC turning workholding options by clicking the image below.

Please come back for our next installment in our series on Shop Efficiency.

Until next time ... Happy Chip Making !!

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Shop Efficiency Part 1 : Cutting Time VS. Workholding and Fixturing

It's the age old manufacturing quest ... how to reduce the cycletime and machine parts faster. And although cycletime is a major factor in the making profits equation ... concentrating too much on cycletime can sometimes make you miss the bigger problems ... the bigger deficiencies in the shop ... the bigger money wasting issues. While you are trying to shave seconds off the machining ... the time your machine spends not running is hands down a much bigger problem. Any machine not cutting is burning money and profits. It's easy to focus attention on cutting speeds and feeds ... it's a fairly obvious item especially for non-professional metalworkers. The fact is, however, every second or even minute you shave off the cycletime is probably no match for the large quantity of time you're machine spends not machining.

What is the BIGGEST cause of your machine not cutting chips ??
The biggest contributing factor for shop machines not cutting chips and therefore making money (  other than not having work for the machines ) are primarily load / unload operations and changeover of the machine from one job to another.

We are starting a new series here in our Making Chips blog to deal with these biggest money wasting areas in almost every shop ... fixturing and workholding. Whether it's the time needed to changeover the machine from one job to another ... or the time required to load and unload the part ... non-machining time is the biggest profit killer in any shop.

To start things out ... I would invite you to take a walk out to your shop floor ... and count the number of machines that are running? ... how many IN-CYCLE lights are lit? I am betting you will be amazed at what you find. And if you look deeper into why the machine is not running ... the reasons can usually be classified into two categories. The machine is being set-up to run production ... or the workpiece is being loaded for machining.

Everywhere people are jumping on the "lean" manufacturing bandwagon ... as they should ... and striving to achieve the 80%-85% percent "in the cut" time target. The fact of the matter is that lean manufacturing goes well beyond just direct chip making. The time spent ... or lost ... in changeover or part loading / unloading ... is probably a bigger profit losing factor than the time the tool spends in the cut.

This series will pull from our shop floor experiences to talk about the various areas of workholding for both milling and turning and machine / fixture changeover ... two topics that are certainly inter-connected. We will publish new articles interspersed with our other topics of interest ... so we invite you to check back frequently and keep up with the discussion.

Series Topic #1 : 
Bringing The VMC Machine Table 
Into the 21st Century

If you take a look at the table on your new VMC ... and compare it to the table on a 1940's milling machine ... you'll quickly notice that not much has changed.

T-SLOTS, T-SLOTS and more T-SLOTS. Not much has changed in the design of the milling machine table since around 1940 ... and that's our first issue to tackle.

While no one will deny that the T-SLOT is an essential element in the table design ... in today's day and age we really need to think outside the box ... or in this case outside the T-SLOT. A couple flaws enhanced by relying on the T-SLOT design include not utilizing all of the space available in the Y axis ... and not having the flexibility of positioning fixturing anywhere on the table to maximize the whole table surface. The first step in accomplishing this is to change the table surface.

One way of altering the surface of the machine table is to use a sub-table ... made from aluminum tooling plate or other suitable material. The main criteria is that the material is durable ... while being fairly easy to machine because we will want to machine a variety of locating options into the sub-

table. The two biggest advantages with a sub-table as mentioned above is that we now have the freedom to machine locating components to accommodate a wide variety of fixturing ... we can more easily utilize all the area of the table surface ... and we can always remove the sub-table and go back to the original table configuration if required. Some of the major points for consideration when considering a sub-table and it's design :

1. Material : durable yet fairly easy to machine ... aluminum tooling plate is one recommendation.
2. Size : it should cover the majority of the table ... thickness should be kept to a minimum as to not reduce the Z axis travels by an unreasonable amount ... but thick enough to accommodate our locating components and maintain rigidity.
3. Weight : aluminum will keep the weight down ... but lifting components should be included in the event the sub-table needs to be removed or re-installed.

   

   Locating pins can be used for
   T-SLOT alignment

4. Locating the sub-table can either be done with keys machined into the bottom surface or with the use of locating pins and dowels that can be used in conjunction with the original table T-SLOTS.
5. Once the table is installed ... it may be necessary to skim the top surface to insure it's parallelism with the machine axis. Keep this in mind when determining the size of the plate and the travels of the machine to allow for this type of machining. Periodically ... this may have to be repeated if excessive wear of the table surface occurs. Also make sure to account for this when selecting and installing your locating components ... which will most likely be hardened materials and not easily machined ... and will need to be installed below the top surface of the sub-table.

Best Ways to Utilize Your New Table Surface

Now that you have transformed your table surface into a 21st century table ... how can you get the most out of it? That really is only limited now by your imagination and design capabilities ... but here  we will tackle what we would consider the top option.

Our recommendation ... we have used this system extensively ... is to utilize fixture plates located and clamped by a "ball lock" system. Fixture plates should be used for everything mounted to the sub-table ... from a simple vise to multiple vises to dedicated fixturing. This allows for greater flexibility 

for positioning of workholding components and allows for quick changeover to other workholding components. 

The ball-lock system allows for quick and accurate positioning of the fixture plates to the sub-table. When designing the sub-table surface ... create as many ball-lock receiver positions as possible to allow for multiple positioning options for your various fixture plate assemblies. You can machine and install these receivers prior to mounting the sub-table ... but they can also be machined in place as their need arises.

Fixture plates can also be made from the same aluminum tooling plate material used for the sub-table. They should, of course, be quite thinner for weight considerations and should always include some kind of lifting component. Handles, as the ones included in the illustration, may need to be removable with a quick attachment mechanisms to reduce their interference in the machining motions. 

If you have an HMC ... you can take the same lessons learnt here and apply them to your tombstone or angle plate. Rather than using the standard "vise tombstone" ... a tombstone which utilizes fixture plates can open up new possibilities for your HMC as well.

Changeover Advantages

As mentioned above, the cycle start light goes out and the profit stops flowing when the machine is being changed over from one job to the next. The system described above can have a massive impact in reducing that downtime. Take for example the simplest task of working with a vise. To remove the  the vise ... just un-clamp the plate with the vise and remove it. When re-installing it ... just lock the plate with the ball-lock system ... no tramming ... no indicating ... no center locating. The ball lock system locates the vise in a known position in seconds every time.

The same applies for all your fixtures ... they mount in seconds in known positions. Fixture design will also be improved because the know facets of the fixture plate location and much of the needed configuration is pre-determined. With pre-set variables in place ... your engineering mind will run rampant and you'll be exploring many more time and money saving options as you go down the road.

Seems Like a Lot of Work and Expense

The above statement is true ...  but it's not easy to get from 1940 to the 21st century. The fact is that once you have completed the transformation ... the possibilities for added efficiency are endless and the reduction of lost machining time will be fantastic ... the payback and ROI will be fast. You will have new flexibility to :

1.  Utilize more of the machine table and Y axis available stroke ... more chip making means more profit.
2. Quickly and easily mount your fixture plates making for faster changeovers ... which means more time cutting chips ... and making money.
3. Have new capabilities to mount multiple jobs with multiple fixture types ... easily run more than one job at a time.
4. If utilizing a 4th axis ... the new table design will give you more positioning options and result in faster mounting and removal of the 4th axis table.

Final Thoughts and What's Next
As you can see from some of the ideas outlined here, changing the surface design of your machining center's table can have quite an impact. While everyone is concerned with shaving seconds of the chip making ... shaving hours off your set-up's and changeovers will have an even greater impact on your bottom line. We hope that some of the ideas outlined here spur on your engineering juices allowing you to realize even more efficient fixture designs and ideas.

Make sure to return and check out other articles in this Series that will deal with fixturing and workholding ... for both turning and milling. We'll touch on things like vises ... face drivers for turning ... chucks and chuck workholding ... and much more.

After all ... we're MACHINISTS ... WE BUILD THINGS !!

Until Next Time ... Happy Chip Making !!

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Chip Removal at Your CNC Machine - AIR vs. WATER

A standard component of almost every CNC machine in almost every shop is the AIR GUN. They exist in a variety of forms and power ranges ... but are the tool of choice for cleaning chips off workpieces and areas of the machine itself. Fast and easy to access ... easy to configure and expand.

But are there any serious drawbacks to the use of the air gun at the machine?

As a former CNC field service technician ... I can emphatically state YES !! I would say that the air hose and air gun are one of the leading causes of major CNC component failures such as backlash and ball screw replacement as well as other axis positioning inaccuracies caused by machine way failures due to scoring. The innocent act of blowing off those chips can actually be one of the more destructive acts a machine operator can do to the machine. Why?? Here's a brief run down of some of the more common problems ... as experienced first hand from my experiences "in the trenches".

Backlash and Ball Screw Replacement
Of all the damage I have witnessed due directly to air gun use ... the need for the replacement of the axis ball screw assembly is by far the most common. Now for the most part I'm not talking about

simply blowing off the chips at the end of the machining operation ... I am primarily talking deep-cleaning the machine. Cleaning the machine and machine table table during a change over ... cleaning the chuck getting ready to install the collet assembly ... the "before the weekend" type cleaning of the machine where the operator may be charged with cleaning the machine from the weeks activities and is using the air gun extensively to gather the chips and "deep-clean" the machine. This type of extensive chip blowing will inevitably lead to the chips being blown into areas not designed to handle them. Perhaps the chips build up in a corner ... out of sight ... or under a way cover or find their way into a telescoping way cover. Looks clean ... but these chips are hiding and waiting. As new machining starts ... the motion of the machine forces the chips deeper and deeper into those areas until eventually they find their way onto the ballscrew where they "work their black magic". The wiper systems for both the machine ways and the ballscrew assemblies are not designed to stop chips being forced in under pressure from the force of an air gun ... but rather are designed to be effective in conjunction with the water flow of the coolant. What starts out as some axis backlash will some worsen and eventually will require the replacement of the ballscrew assembly.

Axis Way Scoring
In conjunction with the destruction mentioned above ... a different scenario occurs when the chips get lodged between the way covers and the machine ways. As the axis moves ... the chips dig and score the ways of the machine. What starts out as some simple score marks are soon magnified as more chips and more metal shavings lodge in those scores and they deepen and worsen and so on and so on and so on ... until the damage is extensive. This type of damage is a much harder to remedy ... the ways of the machine cannot simply be replaced. Now the repair consists of re-scraping or re-grinding the ways ... a major machine rebuild ... or replace the machine tool completely.

Other Common Component Failures

Over the years I have witnessed many other component failures that I would attribute directly to the use ... or over use ... of the air gun by the machine operator. These range from electrical components where chips were blown into cabinets or through seams of cabinets ... CNC lathe turret issues because chips had found their way into the indexing mechanism ... and ATC issues where chips were interfering with the tool change mechanisms. In short ... excessive use of the air gun and blowing of the chips inside the machine enclosure is very destructive ... and expensive !!

The Better Solution - COOLANT
The fact that blowing chips is a destructive act ... doesn't help with the everyday need in the machine shop and at the machine to clear away and deal with the metal chip issue. But I can definitively state that COOLANT and WATER FLOW is a much better alternative. One easy way to eliminate the overuse of air pressure is to provide an alternative like the following.

Create a coolant hose line by installing a T-joint right after the coolant pump. Attach a standard garden hose to the T and run the hose to the front of the machine. Install a standard garden spray nozzle at the end. Now when the coolant pump is on ... the operator will have pressure and in essence a garden hose with coolant flowing at his station. Instead of using the air gun in all instances ... he now has the option of using the coolant as a cleaning medium. The water flow is a much better and safer alternative to the high pressure air gun. BUT NOW IT'S UP TO ALL TO INSURE THE COOLANT MIXTURE IS MAINTAINED. With a healthy coolant mixture ... another benefit is the application of oil to the areas where the coolant is sprayed. Instead of leaving behind metals chips and shavings ... the spray will leave behind a coating of beneficial lubricating oil.
The flow and lesser pressure of the coolant hose provide a much safer and still as efficient chip removal alternative.

Blowing chips seems like such a simple act ... and one that is so common at the machine. But given a more in-depth look ... one can certainly see the possible destructive side effects this simple act can have on the machine tool. If you are in a production environment ... no doubt you have even experienced these destructive end results first hand.

I hope this glimpse into the "real world" can start you and your shop thinking in the direction of utilizing coolant and coolant spray as a chip cleaning alternative. Your machine tool will thank you !!

Until next time ... Happy Chip Making !!

Kenney Skonieczny
Kentech Inc.

At Kentech Inc. we are MACHINISTS who create Real World Machine Shop Software.

Who creates the machine shop software guiding your shop's future ??
Check out all our REAL WORLD CNC & MACHINE SHOP titles at 

www.KentechInc.com

Brief Overview - Automatic Corner Override (G62)

When milling, have you ever experienced chatter and poor surface finish when you are attempting to machine an inside corner radius using the same feedrate as the rest of the workpiece?

Oftentimes, this results in the programmer having to decrease the cutting feedrate in the blocks where the tool cuts in the corner areas. Is there another way to have this done automatically ?

The most common situation above occurs when cutter compensation (G41 or G42) is active and you are attempting to cut in a corner where the toolpath inside radius and the TNR offset value are of similar size. You can use the machine to calculate an automatic decrease in feedrate using the G62 - Automatic Corner Override command ( This is a Fanuc G code ... check your programming manual if you are programming a non-fanuc compatible machine ... there is probably a similar command.) When G62 is commanded, the machine adjusts the feedrate automatically to maintain the cutting quantity per unit time in the corner. This often results in improved surface finish without the intervention or alteration of the programmed feedrate.

A couple of notes for G62 use :

1. Once commanded, G62 becomes MODAL and must be cancelled by commanding G64 (normal cutting mode) or by Power Off as G64 is usually the normal power on mode.
2. G62 can only be used effectively in conjunction with Cutter Compensation - G41 / G42.

Until Next Time ... Happy (and accurate) Chip Making !

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Backlash and Your CNC - Things You Need to Know

( NOTE : This article references FANUC controls but is basically applicable to all CNC controls. )

A machine is a machine is a machine. Just because the words CNC are attached to your machine tool doesn't mean it doesn't get old or lose it's accuracy. And one of the main reasons your CNC machine losses it's accuracy is due to the ever infamous backlash.

What is backlash ?
The axis motion that makes up your machine tool is done through the use of ballscrews attached to your machining center's table and spindle housing or your lathes tool turret. The nut for the screw is usually attached to the table or turret and is connected to the ballscrew which is connected to your drive motor. As the motor turns the ballscrew, the nut moves the table or turret and your machine has motion. All ballscrew assemblies have some "slop" or backlash at assembly - the match between the screw and the nut. Basically backlash is the amount of motion the screw has to make when reversing direction before the nut and therefore the table or turret start to move.

How is backlash compensated?
Using the machine tools CNC controller, the builder can tell the controller how much motion is lost when the axis reverses direction due to the backlash. This value is stored in the machines parameters and when the particular axis goes to change direction, it looks in this parameter to know how much motion it needs to have (how many revolutions of the screw it needs to make) before the axis will physically start to move. The value of the parameter is usually in MM, although they may be in INCH settings in some instances

Why should I care ?
As the machine tool wears or as contaminants get onto the ballscrew and therefore in the nut, the original backlash settings lose their accuracy and therefore effect the accuracy of the machine tool. Positioning problems arise, straightness problems arise, as do a host of other related problems. Basically, the machine does not meet the specs like it did when it was new.

As mentioned above, sometimes contaminants can get onto the screw and then get carried into the nut. Although most nuts are protected against chips and debris, poor conditions can sometimes force the debris into the nut causing premature wearing of the screw and a pronounced backlash problem. Those contaminants can range from coolant to cutting chips. That is why it is essential to keep the machine areas clean and free from an excessive amount of chips. If chips are allowed to accumulate, they can become packed and when the machine tool moves, it forces the chips under guards and into areas where they shouldn't be. Eventually they get forced into the screws and nut areas causing un-repairable problems. Ballscrew replacement is not a cheap repair. Keep the expression: "An ounce of prevention is worth a pound or cure" in mind when planning your maintenance efforts.

What can I do about backlash ?
The normal method for adjusting the machine's backlash involves adjusting the backlash parameter values. This can be done by a qualified technician or you can give it a try. Outlined below is a brief but complete explanation of how to check for backlash and how to adjust it in FANUC controlled machine tools.

How often should you check it ? Recommended time frame would be about every 3-6 months. If you create the following sample programs in your memory and leave them there or upload and download them from a shop floor PC, you shouldn't spend much more than one hour or so keeping your machine accurate and at the same time you'll be checking for any other damaging problems. For example, if you see the backlash changing drastically, you might find a way lube problems or chip build up problem before they cause bigger problems.

How much backlash compensation is acceptable ? As mentioned above, all machines have some backlash adjustment, even when brand new and at ship time. As the machine wears, that value needs to be increased. Normal wear might have .005" - .010" adjustment in a ballscrew. If the value needs to be more than .010", it might be time to take a deeper look. Also, you need to check the backlash at various areas of the screw as it might be wearing more in one area than another. One example might be on a machining center where the set-up people always mount the vise or fixture in the middle of the table. Looks good but also causes a massive amount of wear in one confined area. the best scenario is to mount the vise or fixture all over the table, changing the location for every job - spreading the wear around evenly.

The best way to check the backlash is to first clear out the current parameter value in the control. The various parameter numbers for the variety of FANUC controls are listed further down in this page. First, write down the current values, then clear them by setting them to zero. Then make the machine move through the memory mode. We have found discrepancies in the past between the machine's handle or MPG mode and the memory mode, so we recommend you run the machine through MDI or through the machines memory mode. Below are a couple of sample programs for FANUC controls that you can use to gather your backlash data. Remember, the backlash is the amount of wasted motion when the particular axis changes direction.</p>
<p>If possible, check the backlash at different areas of the screw. On a machining center, mount the block in different areas of the table and check. On a lathe, check the backlash as various distances away from the chuck. If the values are different in the different areas, this could mean that the screw is worn in one place different than others. On a lathe, this tends to happen close to the chuck where the majority of the cutting is performed. You can's do much about to prevent it on a lathe but on a machining center, you can help yourself by mounting the chuck or fixture in various places on the table to allow for even wear. If you find big differences in the backlash in different areas, it may be too late and you may have to replace the screw.

Machining Center Backlash Adjusting Program.
If you have a Vertical or Horizontal machining center, the following program will give you an idea of how to create a program to test the backlash for each axis.

The following is a sample program for the X axis. Start the program with an indicator mounted to the spindle, touching a block mounted on the table, touching the right side of the block.

You can let the program run a couple of times to make certain that you get the same readings at the M00's in the program. The difference between Reading #1 and Reading #2 is the amount of backlash in your X axis.

You can use the same style program making changes as required to perform the same function for the other axis as well. Basically, you just want the machine to move one way then back, stop so you can and collect the indicator reading, then move the other way and back and collect that reading.

CNC Lathe Backlash Adjusting Program.
If you have a CNC lathe, the following program will give you an idea of how to create a program to test the backlash for each axis.

The following is a sample program for the Z axis. Start the program with an indicator mounted to the spindle or chuck, touching a block mounted on the turret or the tool turret itself, touching the spindle side of the block or turret.

Once you collect the value and know the backlash for your machine, you'll need to adjust the parameter values. Parameter values for FANUC controls are usually given in MM  values, without the use of decimal point. So, for example, a parameter value of 30, actually means .030 mm - the decimal point is imaginary and placed three places from the right. You can use the following conversion formula to change your backlash data to mm, then enter that value into appropriate parameter - don't forget to drop the decimal point and add any zeros as required.

MM = inch x 25.4

For reference, 1mm = .0394 in.

On a CNC lathe, the value can either be a radius or diameter value. Since there is no easy way to tell, input a radius value then re-run the test program. Adjust as necessary and make a note so next time you will know.

When you're done, you should re-run the particular axis program again to double check that you did the backlash adjustment correctly. When you re-run the program, you should see less than .0001" backlash.</p>

FANUC Backlash Parameter Numbers.

Listed below are the parameter numbers for the various FANUC control models. One note, lathe controls are T models whereas machining centers are M models.

FANUC Version 6T :

X Axis = Par # 115

Z Axis = Par # 116

FANUC Version 6M :

X Axis = Par # 115

Y Axis = Par # 116

Z Axis = Par # 117

4th Axis = Par # 118

FANUC Version 10/11/12T :

Par # 1851

Seperate line for each axis.

FANUC Version 10/11/12M :

Par # 1851

Seperate line for each axis.

FANUC Version 0T :

X Axis = Par # 535

Z Axis = Par # 536

FANUC Version 0M :

X Axis = Par # 535

Y Axis = Par # 536

Z Axis = Par # 537

4th Axis = Par # 538

FANUC Version 16/18/20T :

Par # 1851

Seperate line for each axis.

FANUC Version 16/18/20M :

Par # 1851

Seperate line for each axis.

NOTE : This 16/18/20 series of control can have a seperate backlash amount when moving at a feedrate and for moving at the rapid rate. This is an option - check with your machine tool builder. If this is the case, Parameter number 1851 is for feedrate and # 1852 is for rapid. You can use the programs above, just change from G00 to G01 and add a feedrate to test for the feedrate backlash amount.

Until Next Time ... Happy (and accurate) Chip Making !

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