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SEAGAMES 2009
important CNC feature can be applied in at least two ways. For example, program zero can be assigned in the program or through some form of offset. Tool length compensation offsets can be specified as the tool's length or the distance from the tool tip to program zero in Z. Cutter radius compensation offsets can be specified as the cutter radius or the deviation from the planned cutter size. And many CNC words can be specified with or without a decimal point.
Additionally, there are those CNC features that have been developed for a niche market. Conversational CNC controls that are programmed on the shop floor make it easy to develop programs when programming must be done during setup. Tool length measuring probes are designed to measure tool lengths during setup for those applications when tool lengths cannot be measured off-line. Apparatus such as bar feeders, automatic loading systems, in-process and post-process gaging systems, and tool breakage detection systems all facilitate unattended operation.
The choices related to each CNC feature make for a great deal of flexibility. The same CNC machine tool and/or control can be applied to a variety of applications. However, with flexibility comes the potential for confusion, controversy, and misapplication. During my CNC courses, students often get into heated discussions regarding the pros and cons of even the most common CNC features. What makes perfect sense to one person seems wasteful or unfeasible to another.
The most basic reason for the controversies that surround certain CNC features has to do with company type. Knowing the subtle differences among company types will help you understand why there are so many ways of handling certain CNC features and will give you an appreciation for another company's differing ways of handling applications.
Product producing companies get their revenue from the sale of a product. In almost all cases, the actual cost of operating CNC machines is one step removed from how the company makes money. In fact, it may be difficult for manufacturing people in some product producing companies to determine each CNC machine's shop rate (the hourly cost for machine usage). Product producing companies commonly have the luxury of adequately tooling up for the component workpieces they run. Most perceive machine up-time (productivity time) as the highest priority. For this reason, they commonly staff their CNC environments with enough people to ensure that their CNC machines run workpieces for as great a percentage of time as possible. Product producing companies tend to have the most complicated CNC environments since they often employ a wide range of CNC machine types for a variety of processes. Many also have CNC machine tools in their toolrooms and research and development departments.
Companies that produce production workpieces for other companies, commonly called contract shops or job shops, generally get their revenue from product producing companies. Manufacturing costs are directly tied to the workpieces being machined, and job quotes are based on the shop rate for the specific CNC machine tools to be used. While up-time is still important, most job shops have a slightly different set of priorities. Since most are quite small (under 50 people), they tend to expect their CNC people to perform many tasks required to get and keep their CNC machines running. It is not uncommon for the person operating a CNC machine to program, set up, verify the program and run every workpiece in the lot. Since they tend to specialize in specific machining operations, job shops often have simpler CNC environments made up of but a few different machine types.
Tooling producing companies specialize in the manufacturing of tooling needed for all forms of production machinery. Die shops, mold shops and companies that produce cutting tools and fixturing are among the tooling producing companies. Like job shops, since tooling producing companies tend to specialize in a certain kind of tooling, they commonly have simple CNC environments made up of only a few different machine types. Also like job shops, they tend to expect their people to perform many CNC related tasks. Many do not place near the emphasis on machine up-time as job shops and product producing companies. It is not uncommon to see expensive CNC machines sitting idle for days if they are not currently required.
Prototype producing companies relieve product producing companies of the need to permanently staff a research and development department to make the prototype component workpieces and assemblies needed to test a new product design. For this reason, more and more companies are specializing in the production of prototypes.
COPYRIGHT 1996 Gardner Publications, Inc.
COPYRIGHT 2004 Gale Group
Additionally, there are those CNC features that have been developed for a niche market. Conversational CNC controls that are programmed on the shop floor make it easy to develop programs when programming must be done during setup. Tool length measuring probes are designed to measure tool lengths during setup for those applications when tool lengths cannot be measured off-line. Apparatus such as bar feeders, automatic loading systems, in-process and post-process gaging systems, and tool breakage detection systems all facilitate unattended operation.
The choices related to each CNC feature make for a great deal of flexibility. The same CNC machine tool and/or control can be applied to a variety of applications. However, with flexibility comes the potential for confusion, controversy, and misapplication. During my CNC courses, students often get into heated discussions regarding the pros and cons of even the most common CNC features. What makes perfect sense to one person seems wasteful or unfeasible to another.
The most basic reason for the controversies that surround certain CNC features has to do with company type. Knowing the subtle differences among company types will help you understand why there are so many ways of handling certain CNC features and will give you an appreciation for another company's differing ways of handling applications.
Product producing companies get their revenue from the sale of a product. In almost all cases, the actual cost of operating CNC machines is one step removed from how the company makes money. In fact, it may be difficult for manufacturing people in some product producing companies to determine each CNC machine's shop rate (the hourly cost for machine usage). Product producing companies commonly have the luxury of adequately tooling up for the component workpieces they run. Most perceive machine up-time (productivity time) as the highest priority. For this reason, they commonly staff their CNC environments with enough people to ensure that their CNC machines run workpieces for as great a percentage of time as possible. Product producing companies tend to have the most complicated CNC environments since they often employ a wide range of CNC machine types for a variety of processes. Many also have CNC machine tools in their toolrooms and research and development departments.
Companies that produce production workpieces for other companies, commonly called contract shops or job shops, generally get their revenue from product producing companies. Manufacturing costs are directly tied to the workpieces being machined, and job quotes are based on the shop rate for the specific CNC machine tools to be used. While up-time is still important, most job shops have a slightly different set of priorities. Since most are quite small (under 50 people), they tend to expect their CNC people to perform many tasks required to get and keep their CNC machines running. It is not uncommon for the person operating a CNC machine to program, set up, verify the program and run every workpiece in the lot. Since they tend to specialize in specific machining operations, job shops often have simpler CNC environments made up of but a few different machine types.
Tooling producing companies specialize in the manufacturing of tooling needed for all forms of production machinery. Die shops, mold shops and companies that produce cutting tools and fixturing are among the tooling producing companies. Like job shops, since tooling producing companies tend to specialize in a certain kind of tooling, they commonly have simple CNC environments made up of only a few different machine types. Also like job shops, they tend to expect their people to perform many CNC related tasks. Many do not place near the emphasis on machine up-time as job shops and product producing companies. It is not uncommon to see expensive CNC machines sitting idle for days if they are not currently required.
Prototype producing companies relieve product producing companies of the need to permanently staff a research and development department to make the prototype component workpieces and assemblies needed to test a new product design. For this reason, more and more companies are specializing in the production of prototypes.
COPYRIGHT 1996 Gardner Publications, Inc.
COPYRIGHT 2004 Gale Group
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