What‘s Happening To CNC Programming Software

This inaugural column offers a broad-brush view of some major trends associated with machine shops and CAM software. Subsequent columns will consider the impact of more specific CAD/CAM technologies on machine shop operations.

CIMdata estimates that in 1999, the worldwide user expenditures for CAM software were $1.3 billion, which is an increase of 13 percent over 1998. For a relatively mature market, this vitality is amazing. The growth is being driven primarily by the need for increased automation to remain competitive in today’s world. Related factors include:

Increased global competition.
The demand from customers for shorter product cycles.
The design of aesthetically appealing parts that contain more complex surfaces.
The introduction of more advanced and higher performing machine tools.
Advanced designs that reduce the number of parts to be produced and inventoried.
The extension of design-initiated technologies, such as solid modeling, into the manufacturing environment.
A shortage of skilled workers that forces greater automation, ease of use, and capture of existing knowledge.

In response, shops are becoming more process oriented, rather than focused on individual operations. Many are re-engineering their internal processes to gain greater overall efficiencies. For example, most shops are adopting paperless manufacturing processes. Use of drawings to transfer part geometry is now less than 10 percent of the total transfers. This shift results in increased product consistency and productivity by minimizing data re-entry and human errors.

Many firms are becoming part of a virtual manufacturing enterprise, integrated with other shops in a supply chain of a major manufacturer. This typically requires increased collaboration and utilization of Internet-based methodologies. Some firms are participating in product design as well as manufacture.

Shops are buying more CNC equipment. Over 70 percent of new equipment investment is now devoted to CNC machine tools. The use of electrical discharge machining and five-axis machining is increasing. In mold and die shops, the use of high-speed milling is increasing rapidly. High-speed milling usually results in a smoother surface finish, reduced hand polishing, and shortened lead time.

To effectively support high speed milling, tool paths are now being generated as a series of B-spline or NURBS curves, rather than as a series of straight lines or arcs between points. This results in smoother movement of a machine tool.

Other enhancements to support high-speed milling include automatic rounding of internal and external corners, slowing the feed rate as excess material is encountered, adding loops to the end of tool paths, optimizing the point distribution, and use of a 3D stepover for constant chip load.

Many shops are turning to online CAM programming on the factory floor by machinists. This approach promotes better utilization of resources, better communication between a programmer and a machinist, and for smaller shops, less dependency on a single programmer. The downside is that programming on a factory floor is distracting, and some machinists may not have the skills for programming.

The movement to knowledge-based machining is a significant trend. More users accept the technology, and major vendors now offer viable products. The benefit is increased programming productivity and more consistent tool paths. The software can be adaptive (establishing and reusing templates for a programming process or operation) or generative (automated use of pre-defined machining rules to develop a program). Concurrently, knowledge-based machining software can be feature-based (a program is developed feature by feature) or parts-based (a complete component is programmed at one time).

Overall, NC software developers are improving user productivity by providing software that is easier to learn and use, more automated, feature rich, flexible, and more tightly integrated with design software. Leading enhancements include: