Calculated Engineering was founded in 1987. Specializing in complex structural aircraft parts, the company currently employs three full-time NC programmers. Accordingly, demand has never been greater for our services. Calculated generates NC part programs for many of the Southern California job shops in the aerospace industry, as well as shops in other states such as Texas and Oklahoma. Our customers expect us to be experts in our field and therefore subcontract to us only the most diffi8cult parts. Since half of the projects that we work on are for production parts, machine time is absolutely critical. Our customers demand that we provide the most efficient NC programs.

We generate NC programs for machining parts cut form 4 inch blocks to 25 foot spars. Materials involved include aluminum, stainless steel and titanium. Many parts require multi-axis CNC machining and for this reason we chose NCL. It provides us with the ability to optimize our NC programs to a degree that would be difficult with other NC programming systems. For instance, NCL boasts over 20 four and five-axis control modes, many of which are found in no other system.

A sampling of tool axis control modes includes: automatic fanning from one surface to the next during flank milling operations; multi-axis lead and slew angle machining with gouge avoidance; and tool axis passing through a fixed point or 3D curve. Other features include automatic feedrate slowdown in corners, 5-axis corner filtering, and the ability to make opposite hand parts.

Typically jobs come from blueprints or from CAD IGES files. Most customers use IGES files, which eliminate many quality problems as there is little change of making mistakes in the interpretation of data. Also, we use SGI video workstations. This way we can have video conferences or modern or faxes with our customers about any data problems.

In addition to NCL, we have added NCCS' PostWorks to our system. PostWorks is a universal 2 through 10-axis postprocessor and postprocessor generator. It converts output from NCL (and from most major CAM systems) into NC data files, which can be used to run virtually any NC device including mills, lathes, EDMs, and CMMs. To verify a new postprocessor, PostWorks automatically creates a solid model of the machine and dynamically simulates the machine's movement. This is especially important to a service bureau as each customer works with a variety of 3 and 5 axis mills and machining centers and we have to develop our NC programs for any of the machines they specify.

Significant Investment
Because CAD/CAM is one of the most significant investments a service bureau can make, we wanted an NC software that was not only state-of-the-art, but one that would continue to be leading edge. NCCS with its NCL software, has a strong and ongoing research and development department that works extensively with users. Recently NCCS added more control of five axis motion to NCL. New modes include: tool axis through a point, tool axis through a curve, and tool axis offset to a guide curve. These new modes shift the tilt and swivel origin of rotation to occur at the designated point or along the designated curve. This additional control is particularly valuable when access to the surface to be machined is limited.

A new mode of surface violation checking has been implemented. In this mode, the surface to be machined is checked along the entire length of the cutting tool. This mode prevents undercutting of convex surfaces while allowing for maximum amount of material to be removed. It also prevents undercutting when the tool axis cannot be aligned with the elements of a ruled surface. All of NCCS' improvements in NCL simplify the programming of complex multi-axis parts and helps us achieve more accurate results. And this is the reason why NCL is such a good investment.