Win-win morale

Culture in an organization builds positively or negatively over time. It takes time to degrade and conversely it takes longer to repair. Employee morale drives the culture in an organization. Every employee has a hidden gem within waiting to be uncovered. Reveal these gems and now a treasure chest of opportunity lies abound ready to be fostered into productivity, efficiency and profits. Empower your employees and earn their respect. Engage your employees and instill ownership. An enthusiastic member of your team is productive. One bad apple can pull many enthusiasts down. Winning over one advocate for the company can convert a whole team. Morale starts from the top down reflecting how management directly handles situations within the company whether they are positive or negative. Implement some of the following ideas to assure you are continually building your morale positively.

All the literature states that the best metrics are a reflection of your company’s goals and this is the correct philosophy for managers and leaders. In the manufacturing area posted metrics should be set up to instill friendly competition between shifts or production teams. Front line supervisors, working together, can encourage competition between teams to achieve small increments towards greater productivity goals. Metrics used correctly can play a vital role in building morale and strong team spirit.

Proving to direct employees that getting on board is worth the effort is very important. Winning teams that meet or exceed goals should be rewarded. Not all rewards are monetary. Recognition and sometimes just a simple “thank you” or reiterating “good job” is the best reward a manager can give. We all work for money but job satisfaction and a feeling of accomplishment means just as much. In addition, prizes and gift cards set in a competitive atmosphere outlined to achieve goals played out on weekly or monthly bases returns high rewards at minimal cost. Think about it, what is the cost of an “out to eat” gift card for two.

How and what you do as a manager directly reflects the attitude returned by direct employees. You should always treat employees how you would want to be treated. Use your knowledge to gain respect and it will be returned. This doesn’t mean you are going to say what they want to hear but you say it firmly and you are fair across the board. Always lead by example.

Because everybody loves pizza this is my favorite. Try “lunch and learn”. Attendance is optional and it is held over the lunch hour. Attendees stand up and offer knowledge to earn their slice of pie. Talk about anything from how to calculate spindle speeds to debates about the parking lot. Anything that has to do with life at the job and stuff you face with pepperoni and anchovies.

A company newsletter can be used to communicate all kinds of pertinent organizational information from changes to employee benefits, next weeks holiday schedule and operational views from the president. The newsletter can be used to improve moral by listing promotions, employee’s birthdays, employment anniversaries to recognizing employees for business and home accomplishments in sections of the newspaper. The list goes on… This is a great way to stop gossip in its tracks.

Effeciently machining high temperature alloys

Large CNC vertical lathe

Inconel, Waspaloy, Hastaloy and other high nickel alloys require very low surface footages and thus machine very slow. Many machining practices can be applied to ease their cutting ability. Increasing insert life, running the highest possible surface footage, depth of cut and immense coolant flow for the removal of heat in combination will greatly increase your productivity. Try some of these tips and apply the ones that best fit your applications and improve your cycle times.

The main focus should be right where the rubber meets the road, type, grade and geometry of the cutting insert. CNMG’s are very common and are usually utilized in every possible citation due to the fact that they can turn and face eliminating a tool change. If you have turned inconel with this insert you notice after a short while a burr begins to build in front of the cut. This material is work hardened and is very difficult to cut. It will eventually break the insert and the build up will have to be removed before cutting can continue. The fix for this is choosing a geometry that leads into the material such as a SNMG at 45 degrees. This keeps the lip from building up and hardening. Another economical factor relating to this geometry is that you have eight cutting edges as opposed to four on a CNMG. Use this geometry for roughing. If you must meet in a corner (i.e. the cut does not pass all the way through the material) then change tools and then eat the corners out with a CNMG. Normally, changing tools is not productive and you would never think this way but due to the long cycle times in cutting these materials a new mind-set is necessary.

Ceramic offers great possibilities if the application is correct. Usually this is a finishing operation due to depth of cut. These inserts do not work well with over-lay type materials due to inconsistencies in the welding. Ceramics have come a long way and a new type of ceramic that cuts well with the use of coolant keeping the part cool is called a whisper. Yes, ceramic with coolant. You want to choose the strongest geometry possible and that is in the form of a button. There is no cutting tip to break off and a circle is just inherently strong. You can see cycle time improvements as great as ten times over that of carbide.

“They are just not built like they use too” referring to the stability and rigidity of machine tools directly influences your ability to machine at high metal removal rates. Back to the rubber and the road analogy, an insert is going to wear at the tip faster than anywhere else no matter what your depth of cut is. If your machine has the rigidity it is far more effective to take a large cut. Choose the biggest insert possible, mainly because this insert will be thicker and will resist breaking.

The most detrimental factor in machining high temperature alloys is the accumulation of heat. Coolant flow and pressure is of utmost importance. Getting the cooling fluid down to where the cutting is actually happening is paramount. The physics of metal cutting is at a molecular level and the cutting fluid must have the minute size to reach this level. A small molecule has this ability with enough pressure. The addition of large molecules in the form of antifoaming and antibacterial will hinder the coolants ability to effectively reach this macro level.

As in any machining process a multitude of variables effect how a part is going to run. The only effective way to find the best practice is trail and error. What works best on one machine may not be the fix for its neighbor.

Adaptive machining

Measuring probe

Previously, I posted an article on reducing operator intervention, which basically outlined ways to automatically make changes to a part set up or process without the operator doing any work. This cuts down on calculator and keypunch errors and increases uptime. With the goal of having a completely computer/CNC controlled operation we can strive to take the operator completely out of the process and observe continuous operation twenty-four/seven with no coffee or rest room breaks and take errors to almost zero.  This is probably an impossible task but using a combination of machine functions, tool life management and measuring probe applications you can custom form a process that is efficient, significantly reduces the occurrence of nonconformities. With the extra man-hours achieved you can now have an operator run two or even more machines.

A measuring probe is at the heart of this operation and it will be necessary to use all of its functionality.  Probes can and should be used for processes other than just in machine CMM functions. They can also be used effectively to set tool heights with grouped tools in the ATC, probe and make wear offsets, setting work offsets and fixture identification.  The list goes on and on and is limited only by your ingenuity. By probing and storing desired data and referencing system variables for position, distance to go or any other pertinent machine data, the value for almost any unknown can be calculated and used in your programs. Study the chapter in your operator’s manual that describes custom macro programming and familiarize yourself with the system variable list and decision-making operators.

Part programming can play an important role in adaptive machining through the use of interrupt programs. Use what you learned about probes and macro programming to make decisions when and where process modifications need to be made then invoke an interrupt call at those points to logically call the correct program in each instance. Be sure to learn the difference between sub program and macro program interrupt calls because each type of call returns to a different position when the interrupt program is complete. Interrupt programs allow for execution of another program while the interrupted program waits. When the sub program or macro program completes, execution picks up in the main program where it previously left off.

This article has solved no problems, not given the answer to questions you may have or typed out any sample programs. It was merely written to open your eyes to the possibilities. Every machining process is different and special attention to your particular case needs to be studied to arrive at a custom fit process. There are many obstacles to overcome if you are starting from scratch. I would suggest getting some experienced engineering help.

Low hanging fruit

Just in time tomatoes

Identifying waste

I’m not talking about determining what belongs in the trashcan. Waste really means anything unwanted. If we are talking about your yard or your garden, then waste is a overripe fruit or an annoying weed. These waste are easily identified and have a simple corrective action: pick the vegetable sooner and pull the weeds as they appear. At work, manufacturing and production waste are sometimes hard to identify. Especially later in the process when you have depleted your improvement ideas and implemented everything you can think of. Are we done or can we continue to improve? Lean manufacturing methods provide tools and ideas to identify manufacturing waste. Now it is time to check these types of operations. There are 7 total non-value added categories. The simple and obvious ones are not in this article. They right are in front of you ripe and ready to be picked. Each different category is about a different mind set or thought pattern needed for identification.

Quality is an up most concern and a top priority in every organization. Look at your process with a different mind set. We are programmed to improve and improve again but there is a point where this is taken to far and it’s called over production. Producing a 32-micron finish where only a 63-micron is required. Now the federate can be increased reducing cycle time and thus increasing value. This is only one example. Carefully review the customer requirements and meet these specifications exactly but do not exceed any. Personally, I have had parts rejected due to a superior surface finish. It’s seems crazy but there was a reason for a 125-micron finish and it was expected to be maintained. I thought we were delivering a higher quality product than our competitors.

Another overlooked waste is unnecessary motion. This type of waste is considered invisible waste. Most importantly, check for waiting or idle times, unnecessary reaching or footsteps, unproductive meetings and redundant paperwork. There can be a non-value adding weed hiding in the darkest corner or the most over-traveled path.

You have to check your tomatoes every day. Pick each when the time is right ensuring that not to many build up on the vine. With this in mind, think about your company’s inventory. Inventory cost money and takes up valuable space. You should strive to pick your fruit just in time. Not to early and never late. Managers are scared of late deliveries and the easy fix is to put some food on the shelf. The correct action is to continually improve process times thus eliminating the need to stock parts.

Waste is everywhere and stepping outside the garden and looking in at your processes in varying lighting will make all the varieties of weeds show their stems. At this stage of growth, pulling them is simple, finding them is hard.

Help: My program is to long!

Heavy roughing machining

We have all as CNC operators experienced running out of program memory. CNC memory is just not very large. So we begin by deleting programs in memory until our new program fits. What if the memory is empty and there is still not enough room for our next part program? To follow is a few ideas to reduce CNC program size.

Check your program for repetitive blocks and replace these blocks with:

1.     A can cycle: All CNC machine controls have the ability to call standard MACRO’s that initiate internal code to repetitively do the same task over and over again such as drilling multiple holes and roughing an OD with multiple passes of equal depth of cut. Some examples are G81 and G73. Consult your owner’s manual for details.

2.     A custom macro: By writing your own custom MACRO utilizing the LOOP and END operators you can customize you own can cycle as described above. Your FANUC controls must be memory system B or above or this option is not available. Consult your programming manual and be very cautious to which common variables you use.

3.     A sub-program: By putting the repeated part of your code in another program it is now only necessary to position the machine correctly in the main program and then call another program (sub-program) to do the repetitive task. It is common practice to switch to incremental mode while in the sub-program and then back to absolute programming again when control is passed back to the main program. All axis movements in incremental mode must cancel each other out or a cumulative error will begin to grow. In other words; position the machine in exactly the same position you started incremental mode when you leave incremental mode.

Lengthy programs that are not repetitive:

1.     NURBS interpolation: If you are machining complex curves, CAD systems will output short line segments to generate a complex profile. This leads to poor surface quality. To create better surface finishes shorter line segments have to be used thus increasing again the length of the program. The CNC controls provides an answer for this: in your part program all you do is describe the curves using control points, control point weight and a knot vector. The CNC control calculates the axis movement from there. NURBS interpolation allows for higher feed rates and finer surface finishes.

2.    Drip feed:  All else has failed and the program is just not going to fit. By connecting to the DNC of the controls a PC can feed the controls, line-by-line, an extremely long CNC program. You will need to understand how to connect to your DNC and have the proper software to communicate with the controls. This requires much more set up than the other options and greater understanding of the machine tool on your part. Sometimes, it’s the only way.

Setting ATC tools as a group

Tool touch off

Setting tool groups is a process of setting the cutting tools in the Automatic Tool Changer in relationship to each other. In order to do this you must choose what is called the lead tool. All tools from this point forward should not be changed or removed and only adjusted through the wear offsets page.

Only in the event of a broken or new tool will any modifications be made to the geometry offsets page.

To set up a machine tool in this manner it is no different than the touch off process that is normally used except for the tool you have decided to use a the lead tool. For this tool it is necessary to make the Z-axis geometry offset 0.0 and set the work offset at Z 0.0 on your part. Now, call up each tool and set the geometry offsets in the Z-axis as you normally would. 

All tools are now set in relationship to the lead tool. From now on only set the lead tool in the work offset at Z zero. You may offset for wear in the wear offsets page.

This is a great time saver. If you have a hundred tools in the ATC they are all set. Every set up now only requires that the lead tool be set.  

It sounds wonderful right. Why isn’t everybody doing this? This process is very error prone to untrained operators and those not used to the process. If your organization decides to switch over to this process then every machine tool should conform to these rules. It is very confusing if some machines are set up this way and others are not. One tool set up incorrectly on either type of set up could spell disaster. 

Make sure that your management team is on board and every employee knows of the change. Otherwise you are asking for trouble.

FANUC's amazing Retract and Recover

Retract an Recover path

Using this very powerful option, a tool can easily be manipulated from a complex part with multiple X and Z-axis movements in order to work around obstructions in the features of the part and then follow the exact path automatically when returned to restart the machining operation from where it left off.  

This is an option and must already be installed on your controls. If it is not FANUC will charge a fee to turn the necessary parameters on.

The following basic steps must be followed in order for the tool to return properly.

Retract: 

1. Automatic operation is interrupted by pressing the feed hold button. You should let the spindle rotate a few times in order to reduce tool pressure.
2. Now press the retract button.
3. Switch the mode switch to rapid.
4. Make no more than 10 different moves UP and AWAY from the part.
5. Press the retract button until it flashes.
6. Press cycle stop.
7. Change your inserts. 

Recover:

1. Turn down your rapid over ride and your feed over ride switches. 
2. Press recover. 
3. Press Cycle Start. 
4. Turn up your feed rate slowly and let the machine follow the original path to the correct position.

Often it is thought that there is nothing you can do when a machine is in tapping mode but let it finish tapping a grit your teeth or hit emergency stop but with retract and recover you can stop tapping instantly and retract out of a hole when you press retract. The machine will rigid tap backwards out of the hole.

Operator maintenance and accountablilty

Daily maintenance log

The first line of defense to protect your most valuable investment is preventative maintenance. Downtime at any work center in your plant is costly in so many ways. First is the cost of repair but it does not stop there: loss in production, the possibility of a late delivery and inevitably this could lead to a dissatisfied or even lost customer down the line. The most costly side effect possible

Preventative maintenance should start with the operators at their machine conducting daily preventative measures by instilling ownership for the parts that they run and the machines that make those parts. It is their livelihood and it is foremost for a manager to clearly pass on an understanding of this principle.

Accountability has its place in every part of an organization. Follow the machine tool builder’s manual as a guide and construct a chart with it as a guide. It ensures that everyone does his or her job. Written documentation that is visually available for others to see is an effective way to enforce accountability.

By making machine operators accountable for the first level of preventative maintenance ensures that your investment in expensive machine tools is first and foremost. Setting up a work center specific checklist that is followed and signed by your operators daily is paramount. A simple check box to be sure that all recommended aspects are covered. Topping off oil levels, changing dirty filters and monitoring pressures and temperatures should be included for operators to initial and sign. 

Daily maintenance log

Managers should follow up at a minimum weekly to ensure operator preventative maintenance procedures have been followed correctly and efficiently. Be diligent in your efforts to support machinist and operators in their endeavor and provide positive reinforcement to support this important initiative. 

Cut faster grooves

Large flange undercut

I remember when I was machining; I used to get in an argument with a fellow machinist about metal removal rates on a lathe verses a mill. He would argue that his milling cutter had 10 inserts. I would come back saying that I had 100 horsepower and my insert was always in the material.

If you think about it… there are advantages to running more than a single insert. Applying this concept to a lathe in turning mode can increase productivity especially on grooves.

Lets think about the difficult situation where the underside of a flange has to be cut from solid material. You have only got two choices: You can plunge out the material with the widest grooving tool your machine can handle or use two opposing tools, one for the topside of the groove and then changing to a reverse tool to do the bottom side of the groove. The first option is slow and very noisy because of chatter. Every one in your shop will run for earplugs. The 2^nd option is inferior because it has to take tiny cuts due to how far the tools are sticking out from the tool post  

I’ve tried and tested every possibility known to man to solve this problem and then I read about chip thinning theory and had a engineering brainstorm. Button cutters exhibit chip thinning around .03 depth of cut.  What does this have to do with anything? For the same reason on a mill you can extend a high feed cutter out 7 times it’s diameter and still run 200 inches per minute. The cutting force is transferred axially, through the spindle instead of side-to-side reducing vibration and deflection during the cut.

In reality, we have to stick out our button cutter or prune tool as it is called on a lathe much farther than 7 times it’s cutting diameter We need further stiffening. You can only weld supporting steel to the cutter as wide as the cutter itself otherwise it will obstruct the cut. Since our prune tool holds a 3/8 button this does not allow for much backing or support.

What if we support our tool with another tool? Now we have to tools welded together with a ½” gusset in between supporting each other. A 1-½ inch wide double button cutter composed of two 3/8” button prune tool on each side with a supporting ½” spacer in the middle. Be sure to leave at least a one inch gap before the button inserts, not extending the support in the middle past this point.

There is more than extra support that is gained by welding these tools together. Now every pass that is taken in the Z-axis to remove material gets to travel 1 ½” less than the groove width. When I explain the path this tool travels to cut you will see that this is a big savings in time when converted to inches per minute.  

We all know that high feed mills travel at incredible feed rates. Since this tool follows the same principle it to will travel very fast up and down. So fast in it will scare the most hardy of operators and pile up chips like no other groover.  

Begin feeding this tool in at an angle. Always keeping .03 depth of cut. On a lathe this equates to .06 in diameter. This is accomplished by zigzagging up and down. Always moving in. A problem arises when you get to more than a ¼ depth of the button inserts. The tool no longer is chip thinning and begins to cut a very wise chip. At this point you will have to slow down the Z-axis feed .05 before it reaches the corner and then kick it back up when you change directions.  

G01 Z-11.0 X49.0 F.11

G01 Z-11.05 F.020

G01 Z-5.05 X48.94 F.11

G01 Z-5.0 F.02

…  

Yes, that is inches per revolution. Rock and roll baby. Let the chips fly. 

Large machined groove

Radial high feed milling

Single point turning

High feed milling

 

Radial high feed milling

They just don’t build them like they used to. Today, machine tool builders try to get the metal removal rate up through the spindle. Use a high surface footage insert, kick up the RPM’s and race through the part. It’s a good philosophy. It enables machine tools to be much less rigid than those of yester year. Comprising of much less casting weight, smaller motors and thinner ways equates to cheaper machines and therefore a smaller investment in tools.

It doesn’t really matter how fast you turn the spindle, these new machines built this way can never keep up with a big hogging machine made 30 years ago with twice the weight and 3 times the horsepower. You just can’t outdo a CNMG 8-series taking a 1-inch cut with a .035 feed rate.

Is there another way to fill up 3 hoppers a day? Yes, fortunately there is if you are facing off material and you have a “C” axis lathe. If you have been single pointing: it’s time to stop.

The following is a generic macro that can be edited for various diameters to really get the meat off. It uses a six-inch high feed mill and is feed in radially in a spiral pattern. It only takes .045 depth of cut but will run at 400 inches per minute. Always climb cut and do not use coolant but blow the chips off the top of the part to remove heat.

%

<MACRO-HIGH-FEED-FACE>

#539=169.5(OD DIAMETER)
#539-#539+7.0(OD CLEARANCE)
#540=124.3(ID DIAMETER)
#540=#540-7.0(ID CLEARANCE)
#541=0.045(DEPTH OF CUT)
#543=#538-#540
#542=[#543] / 8.4]*360(CALCULATE 70% ENGAGEMENT)

G17 G98
G97 S550 M3
#538=1
G94 G54 T0303
G00 X[#539]
Z0.0
G01 W-[#541] F450.
X[#540] H-[#542]
U-2.0
W1.0
G00 X[#539]
M00
...
M30

%

You can add a variable for total depth of cut and loop the program in and out remembering to change directions at the middle to continue climb cutting.

Change the values at the beginning of the program to match your print by editing =#539 etc… Be sure to include the “=” on the MDI screen.

This setup will have a very high chip removal rate and will definitely increase your production and profits

PIctures for process improvement

Set up supports

There is no doubt that humans are visual creatures therefore any where you can implement pictures in operating procedures can make improvements in the occurrence of errors, save time and ease the understanding of any document. Images are worth a thousand words and they can be read in seconds. Any document, no matter how technical or informative can be improved upon by incorporating pictures.

Time reduction on repeated set ups is a common focal point for improving efficiency. Effective and well-worded router operations remind an operator what was used for tooling and fixtures: in the case that it has been months since that set up was ran and in the case that it is a new operator unaware of process obstacles. Imagine now that your router has pictures and effective wording. No type of explanation or technical description can take the place of a well-shot photograph showing all the clamping, parallels and jack stands.

Tooling identification is another area where pictures can quickly used to identify the right tool. Who is going to remember or quickly finds a tool with the designation CXR5500-ABC3 but an image of this tool is almost instantly identified. 

Inserted milling cutters

One Christmas, I bought my wife a vacuum cleaner. I know, a household appliance for a present. Anyways, back to the story. Excited, she began to assemble the toy. I asked her if she needed the assembly instructions but she replied, “No”. After the construction process everything looked kosher but when she went to use it she realized the handle was on backwards. We all had a good laugh and then I began to look at the instructions. It was an exploded view with numbers and a corresponding explanation written in reference to the numbers. A light bulb went off and I realized this is the perfect way to describe the set up for complex parts. The machining cookbook was born and now individual recipes are written for parts in a family of sizes complete with pictures, process map and well-written descriptions.

These are just a few examples where pictures can be used as reminders, set up time reducers and the just plain old Ooops! I forgot to do that “stopper”. Use images anywhere you can!

Improving communication between shifts

Communication log

An important factor in increasing productivity and reducing errors is effective communication between operators during the shift change over. A smooth transition between shifts through the transfer of quality information can make machining up-time numbers remain high and reduce the chance of errors greatly. Implement tools to improve communication and you will continue to exceed manufacturing metrics and goals set forth by your organization.

Nothing works better than face-to-face verbal communication to pass pertinent and important information. The only way to implement this effectively is to overlap shift begin and end times. How much time you allocate depends proportionally on the complexity of your processes. Require operators from each shift to come in 10 minutes early and be at their assigned work center for a transfer of information. Even though this could cost your company overtime pay for almost an hour a week it is well worth the additional financial burden for each employee. Remember the cost of errors is twice the calculated cost due to the fact that the machining center is not producing profit while rework is being run and that time is lost never to be regained.

Written communication cannot be supplemented for because numbers and technical data are sometimes hard for humans to remember. Numbers get crossed and sometimes forgotten. Design a communication log for data transfer of this type. Include pre-thought out fields that are important to the type of operation being done and check boxes for operations done so they are not repeated. Compile a booklet or 3 ring binders and contain all shifts in an orderly manner. This is a very effective tool not only for the operators but in the event of an error it serves as a great root cause analysis data bank for machining operations and when they took place.  

Proper implementation of both concepts, written and verbal, make for the best transfer of information. Use both of these in conjunction with the proper time frame and written down data for your machining processes and errors due to communication have no choice but to go down.

Are you sustaining

The new 5S area looks great! All the S’s are implemented to perfection and now operations at the work center run like a well-oiled machine. This was last month and now the new shelving, although has a pigeonhole for every item; the area is as cluttered as it was prior to the sort and straightening. This scenario seems to get even worse as more and more machines are added to your 5S project.

Typically, a few machines (or production areas) are added each month in order to keep production flowing and spread out the cost of intensive cleanup and organization. 5S is an organizational change not a cleanup process as it is sometimes viewed. Until your organization realizes and undergoes this transformation your 5S’s will continue to deteriorate as you leave one production area behind to start on the next.  

If your company falls into this situation it’s not the machinist or operators fault, its management. Over and over again you must push for change employing fair and consistent encouragement with positive reinforcement and firm criticism when necessary. Only a combination of both will work. Managers know, Mr. nice guy will not work and criticizing consistently will loose all respect.

Just like parenting, managing is a repetitive process.  The best way to make a new process habit is to do it daily. Every day. Like every other company, your 5S project is not the only thing that needs to be reminded upon daily. In addition, information about hot jobs and day-to-day particulars need to be relayed from management down. This sounds like a need for a meeting and it is. Begin your policy of change with a daily kick off meeting that is short and sweet stand up style at the beginning of every shift. Remind employees of the importance of getting involved in sustaining and offer rewards for those who shine. Use this meeting as a moral booster and a getting you head in the game to start work. You can’t loose.

Another suggestion that will work is demoting 5S to 3S for the time being and implementing it over a larger area and empowering operators to this level first before upgrading to 5S.

Utilizing macro statements in G code programs

Standard G code programs work very well so why ever use or learn macro programming. After all, G codes call macros and any operation can be done in the form of a G code program, right? Well that’s not a hundred percent true but for all practical applications you can do everything necessary without ever calling a macro variable.  

Compared to your personal computer, machine controls have very little memory. When long repeated tool paths are necessary very lengthy programs are produced. Sometimes it is necessary to “drip feed” programs from a PC because of memory restrictions. Repeated processes lend themselves well to macro programming through branch and loop NC statements. The code repeats itself over and over until a condition is met. Four lines of code can be used to replace thousands of G code commands.  

In all types of programs readability is important for ease of understanding and organization. Macro variables can be set to any name you wish and held constant throughout a program unless the value is explicitly changed by the program or operator. Imagine the simplicity of use for finish OD diameter in a program that is written FINISHOD instead of 27.759. This is done with the macro command SETVN and written: SETVN 539[FINISHOD]; where 539 is an unused common variable and its value has been set previously. Now code can be executed in the form:

G01 X [#FINISHOD] F0.01;

Macros variables also allow you to pass values to other programs for execution. You can think of this similarly to the R, Q’s and P’s after a G81 command but you can use the data anyway you wish. One macro method causes execution to stop in one program and start another then, return exactly where the initiating program left off. This allows programs to be called that match situations changing from time to time.

Many more options are available. All it takes is a little reading in your programming manual and then a little testing during the learning curve.

manufacturing engineering

Reducing operator intervention

It is human to error therefore we should do as little as possible. Implementing CNC machine tools and robots anywhere that it is feasible is a sound engineering and business decision. Keypunch errors, calculator errors, momentary lapses of dyslexia are just a few of the blunders we face as humans all the time. Machines and computers just do as they are told over and over again. Limiting the amount of data and input an operator deals with daily will greatly reduce manufacturing errors.

Various error checks can be implemented using the NC controls to check for human occurrence errors. A couple of examples have been written about in this blog: “Using the offset range setting as an error check” and "Preempting a common "C" axis error". Preventative checks are limited only to your imagination and ingenuity and you will also discover that these ideas also serve as time savers too.

Don’t wait until an unfortunate occurrence happens to put your thinking cap on. Try and catch these problems preemptively and share your ideas with the world. A few examples are to follow.

Measuring probes can be used for all kinds of location and fixture type checks. Simple macro programs can be written to automatically set work and fixture offsets by finding their location. It is also possible to probe for an identifying feature on machining fixtures to tell the machine which one is loaded on the machine. Then use these identifiers to look up all kinds off related data and offset variables in tables automatically. 

The use of bar code and scanners is a very efficient way to stop keypunch errors and is the best time saver you will ever invest in. They can be used in every process related to industry from inventory and materials through manufacturing and out the door from shipping. Don’t over look this efficient invention for diverting human errors. 

Humans and computers analyze data in different ways and something that is simple to conceive as humans require unimaginable amount of processing power for a computer… and visa versa.  Always implement a checker in visual type processes. Another set of eyes is the best possible way to catch another person at one of those inadvertent times when we overlook details. In this situation the only answer is to increase human intervention.

Lean drawing tools online

BRAINSTORMING

Organize your ideas, create a mind map and share your thoughts prior to a brainstorming meeting then update your ideas in an orderly fashion when your done. All this can be done at Coggle.it. 

PROCESS MAPPING  

Everyone tries to use EXCEL for this chart but the truth is it is cumbersome. Create flowcharts, process maps, swimlane diagrams, and UM charts with ease on gliffy.com. All the objects are available to drag and drop and even a balloon reminds you what each shape represents. Gliffy makes all your charts with ease.  

VALUE STREAM MAPPING

You can really spend a lot of time making use of EXCEL to create a value stream map. It’s just not worth the time but Creately does every type of graph or chart you will ever need with ease. They have great tutorials, explanations and definitions so you will be sure and get the right chart for your project. Make great looking value stream maps at creately.com.

A meeting a day... keeps NCR's away

Conducting a daily ten-minute meeting with direct hire employees sustains moral, improves productivity, encourages communication and information, provides a direction for production and flourishes teamwork. That’s a lot of enhancements. Did I mention it promotes safety? 

Conduct this meeting stand up style at the beginning of the shift. Pick different topics each day to discuss but always use the last minutes to direct and inform about priority jobs and who is to facilitate them during the shift, then end with a moral boosting pep talk… Go Team! 

So, what about reducing NCR’s? Where is this benefit? Error reduction is a side effect that naturally improves by helping workers start with their mind in the game. Letting employees know, it’s time to set homework, girlfriends and football aside. Pick it up again when the  shift buzzer rings.

Good machining practices: Test cuts

This is one of many articles in a series that is meant to reduce setup, program and run time errors by forming good habits as a CNC machine operator. Discussions include properly proving a new program, making test cuts, appropriate inspection techniques and hundreds more procedures that are necessary to master in theory and practice.  

Every machinist, no matter how experienced gets a little nervous when it comes time for a close tolerance finish pass. Typically, the closer the tolerance the more passes one will make, progressively sneaking up on the finish dimension. This can be time consuming but most consider it the cost for a quality part. I do not know of any estimators that factor in the meticulous actions taken by top-notch machinist while figuring part process time for costing.

In reality, it is not necessary to take a test cut but only a test incision into the part geometry. Only cut deep enough to insert the proper gauge into the geometric feature. If you think about it, most close tolerance diameters are a tight fit because another part is going to be pressed inside. Due to this fact, all closely dimensioned features usually have a lead in chamfer. Only cutting to the depth of this chamfer leaves the machinist stock in the case of an error. Even if there is not a chamfer, is it not better to contact your customer and report a out of tolerance dimension only a fraction deep than informing them that the whole feature diameter is in non-conformance.

Machinist should be trained on the proper procedure for test cut / finish cut operations. All machined parts, machine tools and even cutting inserts have a tolerance. The insert tolerance can become a critical factor on very tight fit parts. Inserts should not be changed between a test cut and a finish cut. Many issues can be created by changing the cutting insert from dirt lodged between the insert and the seat to tightening the cam lock screw tighter than the previous operator. In the event a tragedy occurs and an insert has to be changed: blow out the pocket with compressed air and flip the insert over instead of rotating it to expose a new tip. This will minimize the tolerance factor due to indexing.

Another process improvement gained by making a shallow test cut is the fact that more stock is left on the part to be removed during the finish pass, improving the surface finish and creating carbide glaze.

Test cuts can also be employed to inspect the geometric accuracy of machined profiles. Removing a large amount of material for a large cast blank only to find out the programmed profile is wrong or the wrong diameter tool was selected by an operator. Making a light (.01) deep test cut into the material and then inspecting and verifying it was machine correctly is a part saving operation well worth the time and effort. The best way to implement this is to have a separate operation programmed into the part program. Leaving this responsibility to the operator by offsetting the machine to the test cut depth leaves this operation at risk and could be overlooked.

Remember to test cut before you cut.