March 24, 2006 by Jerry Fireman
Facing substantial costs associated with outsourcing, chemical and pharmaceutical firm Merck KgaA turned to a computer-aided manufacturing (CAM) system to cut production time by 50 per cent at its manufacturing facility in Darmstadt, Germany.
Previously, the company used a computer-aided design (CAD) system to design and manufacture fixtures and components for special machines. This method allowed the company to define the geometry of complicated 3D components, but a numerical control (NC) programming bottleneck made it impossible to produce components with anything other than the simplest contours. As a result, the company had to send more of its machining workload out to suppliers at a cost that was considerably higher than doing the job in-house.
Merck manufacturing managers recognized that the lack of efficiency in the computer numerically controlled (CNC) programming process was becoming a major problem. They decided to implement a CAM system that could tightly integrate with the existing CAD system, Solid Edge, and selected Esprit from DP Technology. The solution automatically recognizes the CAD attributes and then creates the tool path necessary to machine the given feature, eliminating the time and potential for error involved in entering them manually. The CAM system also allows the programmer to automatically update the previously defined tool path based on new or modified geometry.
“The time required for programming has been reduced so significantly that it has cut the typical time to produce parts by about half,” said Achim Goettmann, CAD/CAM programmer for Merck.
For example, the CAM system programs a part called a release chamber, which has a number of holes and cylinders that are used to make a neurotransmitter release with slices of organic materials.
“We could have produced the program for this part on a machine controller but it would have taken a long time to define the machining parameters for each of the holes and cylinders,” Goettmann said. “Instead, when we read the file into Esprit, the software understood each of the features and automatically set up the machining parameters.”
The system has also enabled the company to produce parts that it previously had to outsource. For example, a pill controller is used to present pills at various angles so that they can be visually inspected. The grooves that the pills slide in are very complicated 3D contours. The part is excited and the resulting vibrations move the pills along the slots. The middle section has a unique shape controlled by the size and form of the pills being inspected. The creation of the CNC program for this part was the first job done with the system and was intended to determine whether the CAM system was the right choice.
“Despite the complexity of the geometry, this part was very easy to program,” Goettmann explained. “We defined the design of the part in the CAD system and pushed a button to move the geometry into Esprit. The CAM system recognized the standard features such as the holes and bosses. Then I defined the contoured slots as toolpaths. The entire part took only a single day to design and program. Then we set the job up to run unattended on a machining centre overnight and we had good parts the next morning.”
The CAM system recognizes features contained in the solid model and automatically adjusts such information as the diameter and depth of holes that need to be drilled. The company saved additional time by creating tool libraries inside the CAM system. These include all of the cutting tools that are used on a regular basis and “sync lists” that define machine setup parameters. The company also uses the “process manager” to define machining operations that are performed on a regular basis so they can be inserted into any new program.
“The bottom line,” said Goettmann, “is that the job of the programmer has changed from manually entering the code line by line and hoping that an error wasnÃt made, to supervising the work of the computer and making high-level decisions about the best way to machine the part.”
Another benefit, said Goettmann, is that “part complexity is no longer a criterion for manufacturing outside Merck, so we have been able to dramatically reduce subcontracting expenses. By keeping complicated jobs inside, we also have greatly reduced the potential for confusion and misunderstanding between design and manufacturing.”
Jerry Fireman is the president of Structured Information, a technical communications company based in Lexington, Mass.