Eliminate variations & increase efficiency. Start now!
Posted: February 25, 2024 in UNCATEGORIZEDTags: ai, artificial-intelligence, automation, business, technology
The act of qualifying CNC programs is largely related to eliminating variations, which can be a daunting task when you consider how many things can change from one time a job is run to the next.
The more a task is repeated, the easier it is to justify improving it. Most improvement programs begin by looking for the biggest bang for the buck. The benefits provided when improving an often-repeated task will be experienced every time the task is performed, making the required effort to improve it worthwhile. This assumes, of course, that the task is performed in the same manner every time it is performed.
Consider, for example, an often-repeated job that runs on a CNC machine tool. Many companies run a finite number of repeated jobs — over and over again. An improvement made to improve the repeated job will provide the same benefit every time the job is run. But again, this assumes that the job is run the same way every time. A variation can wreak havoc with the expected productivity gain.
Along these lines, companies strive to “qualify” CNC programs for repeated jobs. Once a program is deemed to be qualified, the program should run flawlessly whenever the job is run. Anything that causes a qualified program to fail will be related to some kind of variation. Something is different now than it was the last time the job was run.
For this reason, the act of qualifying CNC programs (or any repeated task, for that matter) is largely related to eliminating variations. This can be a daunting task when you consider how many things can change from one time a job is run to the next.
Workholding variations
The same workholding device must be used each time the job is run. Using a different vise on a machining center or different top tooling (jaws) on a turning center may change the clamping forces used to secure the workpiece, and lead to issues during machining operations. In similar fashion, manually tightened clamps, like vise jaws and fixture clamps, must be secured in the same fashion each time the job is run.
For machining centers, placement of the workholding device on the machine’s table must be consistent each time the job is run. Variations will cause the need for remeasuring program zero assignment values and entering them into fixture offsets.
Cutting tool variations
It can be challenging to eliminate variations with cutting tools from one time a job is run to the next. And admittedly, doing so can conflict with efforts to improve the machining process by employing newer cutting tool technologies. But if CNC programs are to be qualified, variations in cutting tools must be eliminated.
This means cutting tool documentation must be all-inclusive. The person who assembles cutting tools, possibly a person in the tool crib, must be provided with a complete list of components that comprise the cutting tool, and for machining centers, information that illustrates precisely how long each cutting tool must be.
Machine condition
This potential variation is often overlooked. Wear and tear eventually affects how machine tools perform. Be sure your company adheres to a good preventive maintenance program. It will ensure that older machines perform nearly the same as they did when they were new. Examples of machine deteriorations that cause productivity-related issues include gib and way system wear, faulty coolant systems and worn spindle bearings. Additionally, corrective maintenance must be properly done whenever mishaps (crashes) occur to ensure that the machine behaves the same way it did before the mishap.
There are also machine condition issues caused by poor usage techniques. With turning centers, for example, use the style of tooling (right- or left-handed) that causes the force of the machining operation to be pushed into the machine bed — as opposed to pulling the turret away from its direction of support. For machining centers with rotary axes, be sure to apply the rotary-axis clamp in the program (usually specified with an M code) prior to performing any powerful machining operations.
Lot size
A job may run just fine when only a few workpieces are produced. Cutting tools may last for the entire job before showing any signs of wear. But as lot size grows, cutting tools may not last as long as they should — or operators are making an excessive number of sizing adjustments. Indeed, process or cutting tool selections may have to change to accommodate the number of workpieces being machined. Indeed, some companies maintain two or more versions of the program/process based on lot size.
People
The same people will not be involved every time the job is run. Your company likely experiences turnover in workers or multiple people doing the same things, especially during multiple shifts. But as with other variations, varying skill levels of involved personnel can negatively affect productivity. The two general ways to overcome this variation are to improve skill levels through training and/or to lower the skill level required to perform tasks by simplifying to the point that anyone can perform them.
Environment
Even variations in the machining environment, such as temperature and humidity, can cause consistency issues. Consider a shop that is not air conditioned. Jobs run in the winter, when the heat is on, maybe run well when the ambient temperature is around 70ºF. Jobs run in the summer (without air conditioning) may be run at a substantially higher ambient temperature. Operators having no trouble holding size on a job run in the winter may struggle when running the same job during a hot summer.
The six reasons above only scratch the surface of what can change from one time a job is run to another. Here are a few more potential variations:
- Gaging devices – Variations in the selection, quality and condition of gaging devices affect how accurately people take measurements.
- Cutting tool placement in turrets and tool changer magazines – With some machines, cutting tool placement affects program execution time. How long it takes a program to run may vary from one time the job is run to the next.
- Design and process changes – These variations cause the need to re-qualify the program, at least for segments of the program that have changed.
- Company procedures – Changes in the way you expect your people to do things negatively impact productivity (taking and reporting measurements, for instance).
- What else changes? – Again, you must eliminate anything that changes from one time a job is run to the next.
How to integrate #APQP into, #PFMEA , #DFMEA , #PPAP , in order to increase your productivity, and lower manufacturing costs #costeffective given #aerospacemanufacturing production environment.
Posted: August 27, 2023 in UNCATEGORIZEDIn my entire career #aerospacemanufacturing shop floor production #milling #turning #EDM #gearshapping …etc, I have used many methods in the attempt of increasing the productivity of the entire factory or just sections (manufacturing cell area) and lower manufacturing costs. In my case some methods failed to achieve the end scope, and some actually exceeded the realistic set target. (I do strive for perfection; realistically you can remove waste from a process at above 90%).
Let’s run a few scenarios and examples for #quality PPAP inspection on #aerospace shop floor #manufacturing environment.
- Inspecting internal corner radiuses created by the tool’s radius in a milling process- These are features that either cannot be CMM inspected or not #costeffective to be CMM inspected. The #industry fast pace demand requires a more #productive and #costeffective method – using the classic plasti-mold and shadow graph is an obsolete and #timeconsuming method.
As more factories are implanting high precision toll pre-setters like #Zoller (for example). This gives the advantage of measuring the corner radius of the tool in the same measuring cycle, and also setting the tool’s life onto the RFID chip. If these set parameters are not within measured specification, then Zoller’s tool pre-setter will not pass and not write the info onto the #RFID chip. As long as the tool’s radius will keep its profile within the set tool’s life –and this is to be proven within test trials – we can set a longer inspection increment within production environment.
One of the best manufacturing software I ever used, is #Solumina , as per you can imbed inspection plans in within the manufacturing operations and can set inspection checks on “first” and “last” component, from a given production batch of let’s say 12 components, as long at its “flow diagram” function is configured to do so. @Solumina can be set to record a higher inspection increment, then “first” and “last”, in order to increase productivity
An advanced CNC milling turning manufacturing production environment is configured for “Lights out machining” utilizing multitask tooling and automated methods for #costefficiency. So utilizing as much as possible the same tools across various projects on the same CNC machine will drive out #waste and generate #costsavings.
CAM software like @Siemens NX CAM has the ability of feature CAM recognition for #bestpractice #manufacturing methods to standardize manufacturing methods and tooling – basically each CNC programmer that will create a new NC program will use both tooling and manufacturing methods with proven cutting conditions in order to achieve “ right first time” #manufacturing process.
Vericut to check the cycle time and volume the tool removed to set tool’s life once best practice method is proven.
#SAP to release work orders on the shop floor in a set group and given order to accommodate tool life as per #productionschedule.
As long as you have all the above tools, and a solid manufacturing method, than there is no #risk of #quality escapes.
- Bottom angle on blind drilled holes and features generated/formed with porting tools.
As long as you use a @Zoller tool pre-setter — this will check the drill’s tip angle. You do get as standard 140deg. However various tools suppliers will uses between 136deg. up to 142deg. As #DFMEA . I do advise for the depth of drilled holes to be given to shoulder as per it’s more accurate to inspect.
There are various chamfers and angled faces that being generated /formed with a porting tool can be passed for manual checks by inspecting the cutting tool on the #Zoller’s tool pre-setter. Of course use a plug gauge for diameter size and CMM for depths and #GD&T, also various corner radiuses can be passed accordingly measuring the tool’s radius on the #Zoller tool-pre-setter rather than creating a plasti-mold/”wax” on the component’s features and check on shadow graph.
To be continued ….. and revised .
I appreciate your time, taken on reading my post.
Let me know in the comments bellow ….. Your thoughts … ideas..etc .
What is the difference between #Lean and #SixSigma in a machine shop environment.
Posted: May 2, 2021 in UNCATEGORIZED#Lean Manufacturing processes focuses in driving out as much waste as possible. You can never eliminate waste (as in 100%) because waste will always be inherited in processes, even if you invest in new technology , then you can use that technology to drive out more waste.
#SixSigma refers to process variation reduction, meaning… get your process stable enough so it repeats within the variation as tight as possible, closest to the mid limit value, given a set manufacturing process.
As a Manufacturing Engineer, you would ask yourself, how would you implement these principles into a machining process?
I will give you an example of one of the many CNC milling processes that I have worked on, quite recently. I had various shapes into 30 something pocket features with various open and tight tolerance bands, these pockets are equidistant spaced into a ring component…..I won’t go into the details of these features, or the work holdings as per NDA and also this is not the subject now, but you get the idea. It isn’t anything special, normal milling – roughing and finishing.
I have tried different tools for the roughing stage, and I found the Tungaloy TECR160B6MF-34W16-92 Grade AH725, end mills to give the best results so far, combined with the Haimer’s shrink fit tool holder (shrink chuck) with cool jets. Given the tool’s 6 cutting flutes you remove material faster than using a 4 flutes and also the “tool’s core” is stronger. In roughing it’s important to remove the material in a certain sequence to eliminate any potential residual stress, and also generate tool paths in such a way that cutting forces are directed axial and radial in order to lower tool vibrations and also to use the entire cutting flute length in the areas were the workpiece have thin metal so the tool wears evenly through the process.
For the finishing stage I have used the Kennametal Duo-Lock FSDE1600XBCQG Grade KC643M, mainly for the 11 flutes and the SS16SLDL16070M shank for the safe lock system that also allowed to integrate the Haimer Safe-Lock with cool jets shrink fit tool holder. The tool path for the finishing stage is just simple radial engage as it gave the highest tool life, and lowest cycle time.
-Now, this stage can best explain the difference between #SixSigma and #Lean-: To ensure, highest tolerance and to eliminate thermal drift, the tool is recalibrated radially and axially by semi finishing a feature with two parallel faces. The distance between the two face is measured by either a probing cycle that updates the radial tool’s wear and the tool’s length wear, or actually do manual checks and updated the tool’s wear, manually – given the CNC machine capabilities. This actually adds extra cycle time given that the tool is recalibrated for each component, but given the tool’s 11 flutes, this is only being done once. So there is required balance between #Lean and #SixSigma in order to achieve a stable process.
I do believe that certain principles as #SixSigma and #Lean are useful in a machine shop environment, and given the machine’s shop capabilities can be applied to a given level.
I hope you can use this example to improve your process, and eliminate waste as much as possible.
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Posted: January 20, 2019 in UNCATEGORIZED
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Posted: January 5, 2015 in CNC MANUFACTURING CAM SIMULATIONS, CNC MANUFACTURING PROCESS
Adrian Hainarosie C.A.D. Mechanical Designer & C.A.M. Programming C.N.C. Manufacturing. 