be necessary - they generally belong to the features of the program that can be easily edited, such as spindle speeds, cutting feedrates, clearances, etc. program optimization make the current program run more efficiently within the given setup.
When the optimization process is completed, the production run is more than just loading, running, and unloading parts. The operator has to monitor the progress, check dimensions, check tools, replace tools if necessary, adjust offsets, watch the coolant, deburr parts, and do many other tasks.
Inspecting a finished part is one of standard manufacturing processes. Depending on the job, not every part in the batch has be to be inspected, but a certain number of parts in any batch are inspected as a norm. CNC operator may be called upon part inspection as part of everyday duties, or a QI (Quality Improvement) department may be responsible.
In all stages of the machining process, safety should always be paramount.
Always obey all safety rules
Study individual chapters in this handbook. Many of the items briefly described here are presented in great detail, including examples and applications.
| 2 | CNC MACHINE SPECIFICATIONS |
All CNC machine tool manufacturers provide very comprehensive information about each of their products they ship to their customers, mainly distributors, dealers, service providers, and even to the end users. Typically, this information is a collection of various data related to the particular CNC machine tool.
Machine specifications contain data relating to important dimensions, capacities, ranges, restrictions and limitations of the machine tool, not the CNC system. These specifications come in many versions, each being focused to a different purpose of usage. They can be in digital form stored on a disk, or in a reference book that is shipped with the CNC machine.
Most commonly available methods of machine specifications data can be summed up into several distinct categories:
▪Advertising material
▪Promotional brochures - overview
▪Promotional brochures - comprehensive
▪Sales oriented information
▪Service oriented information
▪Machine tool manuals
▪Control manuals
▪Parameters manuals
▪Training material with examples
▪Information specific to the CNC machine
How does all this information that may or may not be included in such diverse groups assist the CNC programmer during programming or the CNC operator during part setup and machining? The answer is ‘selectivity’.
Both CNC programmers and operators need only a very small portion of the overall information in the documentation provided by the control or machine manufacturers. This chapter tries to identify what data and other information are important to the CNC operator working at the machine, and to some extent, to the CNC programmer as well.
No specific machine specifications have been used. All information has been adapted from actual machine tools and is representative of the important features that directly affect CNC programming and CNC machining.
Every manufacturer of CNC machines provides the potential buyer with descriptions of their products, for three reasons - sales, information, and training. Sales definitely dominate. Machine specifications are a collection of data regarding a particular machine tool, without the control system. Control unit specifications, on the other hand, provide information about the control itself.
The following sections will concentrate on the three major groups of metal-cutting CNC machine tools:
| ▪ | Vertical Machining Centers | VMC |
| ▪ | Horizontal Machining Centers | HMC |
| ▪ | Lathes and Turning Centers |
Each group will cover specifications that are common to all machines, such as maximum and minimum axis motion or the range of spindle speeds. Each group will also cover specifications that are unique to that particular group of machines, such as indexing axis for horizontal machining centers.
In all examples, only those features that directly affect the work of CNC programmer and/or CNC machine operator will be described.
To make the specifications easier to read, the data will be collected in the form of tables.
This group of machining centers is often identified by the abbreviation VMC - Vertical Machining Center. VMC is the most widely used machine group in industry and many models, sizes and configurations are available to the end users.
Vertical machining centers are designed mainly for machining as the XY motions at a given depth. This is called 2-1/2 axis machining. Most of these machines also allow simultaneous XYZ motions. This feature is called 3-axis machining. Because of their design, cutting on sides is limited, unless special attachments are used.
For the CNC programmer, all features are equally important. For the CNC operator, some features are more important than others.
This group of machining centers is often identified by the abbreviation HMC - Horizontal Machining Center.
Only basic data for a 2-axes CNC lathe are included.
While the traditional and