And More - Feature Article:

by Mike Lynch, CNC Concepts, Inc.

Training Issues

"If you train people, they may leave. If you don’t, they will stay… Which is worse?"

Don’t think you are saving your company money by minimizing the training you provide your people. Companies that have eliminated their apprenticeship programs to gain a short term savings got just that - a very short term savings. When it comes right down to it, untrained CNC people are dangerous CNC people. They make you pay dearly for their lack of experience. Poor quality, inconsistent productivity, and crashed machines are obvious symptoms of a confused and under-trained work force.

In reality, money invested in training will return ten-fold. Good working attitudes, fresh ideas, and progressive thinking that come from training will result in improved quality, increases in productivity, good work habits, and a safer working environment. In addition, some of the best ideas for cost-saving improvements commonly come from training.

Admittedly, you may not be able to completely justify the cost of your training program based on the cost saving improvements coming out of training, especially at the out-set. But before you target any area for improvement, before you implement ideas to reduce setup time or cycle time, before you implement changes to process, cutting tools, or work holding devices to improve part quality, indeed, before you embark on any cost savings program, consider improving your in-plant training capabilities. The benefits that can be achieved by increasing the proficiency of your CNC people will easily out-weigh any other single change you can make in the CNC environment!

Proficiency dictates level of productivity

Without exception, the productivity of any task is directly related to the proficiency of the person performing the task. This is true in any area of manufacturing. The time it takes an inspector to correctly check a workpiece is directly related to their measuring proficiency. The time it takes a secretary to type a lengthy report is directly related to their typing proficiency. The time it takes a design engineer to draw a workpiece on the computer aided design (cad) system is directly related to their cad system proficiency.

Nowhere in manufacturing is this premise more true than in the CNC environment. If a programmer is unaware of some special technique they could use to make their program more efficient, productivity will suffer. If a setup person, does not understand setup time reduction principles, productivity will suffer. If an operator does not know that tool wear offsets can be adjusted during the machining cycle, productivity will suffer.

While these are very basic and obvious points, it is amazing how many managers pay little or know attention to proficiency levels of their workers. And fewer still are willing to invest time, effort, and money in improving proficiency.

Five proficiency levels of CNC

Before you can design a training program to improve proficiency, you must have a solid grasp on just exactly what you currently expect your CNC people to do. Unfortunately, companies vary dramatically with regard to what they expect their CNC people to do. Generally speaking, the smaller the company, the more they expect. Though it is hard to describe firm responsibilities for each CNC proficiency level, this description relates the most common expectations of manufacturing companies today, and should give you a good example of how you can isolate the tasks expected of your own CNC people - in your own CNC environment.

Level one - Ability to communicate intelligently about CNC

Anyone that can affect or is affected by the use of your CNC machine tools should have a working knowledge of CNC usage. When you think about it, this includes many people that are not normally considered part of your CNC environment. Design engineers, manufacturing engineers, tool designers, process engineers, inspectors, assemblers, managers, and foremen are among the many people who should understand at least the basics of how CNC functions. While these people may never be expected to write a program or run a machine, they can dramatically impact the success of your CNC environment.

If, for example, a design engineer, is aware of how coordinates are specified in a CNC program, they can dimension and tolerance prints in an appropriate manner. The classic example of inappropriate dimensioning is related to bolt hole circles. If the design engineer dimensions the bolt hole pattern with a radius and angles, they force everyone else to calculate the coordinates for each hole.

By including these people in your CNC training program, you can eliminate a great deal of confusion among people in your CNC environment, which of course, will lead to better productivity from all involved.

Level two - Ability to operate CNC machines to maintain production

Again, companies vary with regard to what they expect their CNC operators to do. Many limit the operator’s responsibility to maintaining production. Tasks related to maintaining production include:

• general ability to operate machine (power-up, shut-down, manual operation, and a general understanding of buttons & switches and operation procedures)
• un-loading and loading workpieces
• activating the cycle
• adjusting offsets to hold size as tools wear
• statistical process control (SPC) reporting
• tool maintenance (replacing dull tools)

Companies that have medium to high production quantities (lot sizes) commonly limit their operators’ responsibilities in this manner. When it comes to training, the more focused you can be relative to tasks that must be mastered, the easier it will be to develop an appropriate curriculum. If your companies expect little more of your operators than those tasks described above, it should be quite easy to develop the appropriate curriculum. More on the actual curriculum a little later.

Level three - Ability to make setups

Before a CNC machine can begin running production, it must of course be set up. Again, CNC using companies vary with regard to what they expect their CNC people to do. In some companies (especially smaller companies), one person is responsible for everything. This includes programming, setup-related tasks, and actually running production. A company that has very small lot sizes (1-2 pieces) and no repeat business commonly utilizes their CNC people in this manner.

The vast majority of CNC users run lot sizes of between 10 and 500 workpieces, meaning setups will be made on a very regular basis. Many companies will divide the overall task of making a CNC setup among several people. While different people may be involved each step of the way, here we list setup-related tasks that must be completed before production can be run. To be completely proficient with CNC operations, a person must be capable of performing all of these tasks.

• tear-down work holding setup (remove work holding device)
• clean machine of chips and coolant residue make new work holding setup (place new work holding device)
• assemble and measure cutting tools enter cutting tool related offsets measure program zero location
• remove old program from memory
• load new CNC program in memory
• verify CNC program and make corrections as necessary (new and previously used)
• optimize CNC program (if lot size is large)
• explain production maintaining procedures (workpiece loading, offsets, etc.) to operator
• mastery of all tasks related to level one

Obviously, this level requires a much better understanding of the machine’s usage than level one, and the related curriculum will be much more complex.

Level four - Ability to develop programs

While many CNC programmers do not need an intimate understanding of every task described in levels one and two (most do not actually have to make setups and run production), it should go without saying that the CNC programmer must have a very good understanding of how setups are made and production is run. The programmer’s methods will, of course, have a big impact on CNC setup people and operators. In many of the companies I visit, some of the largest gains in productivity are related to enlightening the CNC programmer about programming techniques they can use to make life easier for setup people and operators. All programmers should have a good working relationship with setup people and operators.

Companies also vary with regard to how they expect their CNC programmers to develop programs. If production quantities are quite high, if there is very little repeat business, if programs are quite simple, and/or if only one or two machines are involved, many programmers will develop programs manually at G code level. On the other hand, many programmers will use a computer aided manufacturing (cam) system as quantities drop, the work becomes more complex, etc.).

Regardless of how programs are prepared, all CNC programmers must possess a thorough understanding of manual programming, which is the focus of our given curriculum. Even if a cam system is used, there will be many times when the programmer must be able to read and understand the CNC program generated by the cam system (to make corrections, to alter cutting conditions, and to optimize).

The actual tasks related to programming are too numerous to specify here. With our teaching methods, there are six key concepts a programmer must master in order to become proficient:

• know your machine (from a programmer’s viewpoint)
• prepare to write programs
• understand the motion types
• understand the compensation types
• understand how programs must be formatted
• master the special features of programming
• optimize CNC program (if lot size is large)

Level five - Ability to teach CNC to others

When it comes right down to it, teaching CNC is the major focus of this text. And later, we will address issues related to selecting an instructor, developing a curriculum, and setting up a good learning environment. But depending upon how far you wish to go with your implant training program, remember that your company may not even need to supply an instructor or perform any of the actual tasks related to teaching CNC. You will see in our next discussion that there are many excellent CNC training resources designed to improve the proficiency of your people at each of the previous proficiency levels.

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