CAM Programming System More Than Doubles Machining Productivity
Productivity doubled for Tour de France component manufacturer through the use of knowledge-based machining.
Knowledge-based machining has dramatically reduced the time required to produce high-performance bicycle components that have been used by several recent winners of the Tour de France. When Specialites TA created computerized numerical control (CNC) programs to produce chainwheels, crankarms, water bottles, bottle cages and other components by entering coordinates in the machine, managers found that the machines were being used more for programming than for producing parts.
Alain Breuil, president of the company based in Clamart, France, invested in a new CAM programming system that allowed him to create a user-friendly environment that makes it possible to build a program for a particular chainwheel in minutes by filling in parameters such as its diameter and number of teeth.
The new software has reduced the time needed to program parts from several hours to a minute or two, making it possible to more than double the productivity of the company's Mazak machining centers.
"Automating part programming makes it possible to use our machining centers nearly exclusively for what we bought them for - cutting chips," Breuil says. "The result is that we can produce much more with the same number of people and machines."
When the world's great cyclists come together to compete in the Tour de France, the high level of performance and narrow margin between the fastest and slowest riders means that every component on the bicycle must be optimized to deliver peak performance. For example, the chainwheel is the sprocket attached to the right crankarm that drives the chain to propel the bicycle forward. The weight has a crucial role on the bicycle's performance in a tight race. The chainwheels built by Specialites TA that were used by Tour de France winners save crucial ounces by being made of 7075 aluminum, a high-strength alloy that includes zirconium, manganese and copper and was developed for use in aerospace applications. The manganese and zirconium provide precipitation hardening and solid solution strengthening capabilities while copper provides strength. The performance of these chainwheels is so critical that many competitors use different versions in different stages of the race. Last year's winner, for example, used Specialites TA's chainwheel in the critical mountain stages, the same part of the race where he surged past his rivals during a grueling climb in the French Alps and took a commanding lead in the race.
Critical Need for CNC Programming
CNC programming has long been a critical issue for Specialites TA
because the company is continually designing new products to meet the
special needs of bicycle enthusiasts and nearly all must be produced to
very close tolerances. Breuil has been producing parts on CNC machining
centers since the 1970s. In the beginning, he wrote the programs on
paper tape using G-codes. Using this approach it took one to two days
to create a program for a new chainwheel. Manual programming also did
not allow for graphic toolpath verification, which meant that mistakes
had to be fixed by the programming on the shop floor. Also, the time
required to program in G-codes was continually increasing along with
the complexity of the company's parts. In the middle of the 1980s, the
company began programming through an interface provided by the
controllers of its newer Mazak machining centers from Mazak Corporation
(Florence, KY) - a machine tool manufacturer. The machine control
provides a relatively simple graphical interface that saved time by
eliminating the need to generate individual G-codes and also provided
some verification capabilities. This reduced the time required to
create a program for a new chainwheel to about two hours.
But Breuil said that in the late 1990s, this approach began to lose its luster. "The problem was that the geometry of our products was gradually increasing in complexity and we also were developing new products at a faster rate in the past," Breuil explains. "The machine controller worked well for simpler parts, but as their geometry grew more complex it became increasingly cumbersome. Another problem was that we were increasing the pace of our product development efforts. The bottom line was that we had to use the machine controllers more and more for programming, which left less and less time for producing parts. The utilization rates of both our operators and our machines were steadily dropping. I began looking for a programming system that would allow us to create programs on a personal computer so that we could devote our machining centers to cutting chips. The biggest challenge in selecting software was that we had a wide range of CNC machines, from very old models to the latest tech-nology. The problem was that most of the software packages I checked out weren't able to provide postprocessors that could produce code to drive the older machines and didn't have the ability to allow me to easily create the postprocessors myself."
Software Streamlines Family of Part Programming
Breuil found one software package, ESPRIT from DP Technology, Inc.
(Camarillo, CA) - a CAM software provider - that offered the ability to
build his own post processors. Via a custom post generator, ESPRIT can
easily modify an existing post from the software's library or create a
new post from scratch to suit a new machine. This CAM system also
features knowledge-based machining, which allows it to capture
information from a company's programs and original designs and build a
database of knowledge to automate the CNC programming process.
"The thing that attracted me to knowledge-based machining was that it offered the potential not only to program parts away from the machine, but also to develop macro programs that make it possible to automate the programming of parts that are similar to each other," Breuil explains.
ESPRIT includes a comprehensive macro language with logic, loops and variables. Its associative structure means that a single machining process can cover operations performed under a wide range of machining conditions. In addition, geometry, toolpaths and machining conditions can be defined without switching from one section of the program to another.
Breuil has developed several knowledge-based machining macros that make it possible to generate G-Code programs to machine new members of a part family in a matter of minutes. A good example is the macro that Breuil developed to machine chainwheels. These parts are machined from a block of aluminum. In about one day he developed a macro that allows the user to type in the answers to a few questions such as the diameter of the chainwheel and the number of teeth. The macro then automatically creates the G-Code program needed to produce the new part. The operator then simulates the machining operation on the computer screen prior to producing any parts. Problems are found and fixed in the software so that when real parts are produced, the process is trouble-free. The program is then electronically transferred from the PC to the machining center. The entire process takes only a minute or two. The program dramatically reduces the cost and time involved in developing new products in response to demand by customers or dealers.
EDM and Turning
Breuil also uses the CAM software for all of the other machines in his
shop, including turning centers and Electrical Discharge Machines
(EDM). He uses turning to machine chainwheels and cranks for bicycles
and uses EDM to produce tools for stamping and polishing various
bicycle components. For turning operations, the operator defines the
profile of the part in two dimensions, and then specifies the cutting
sequence from the part geometry. The operator then directs the software
to automatically create the necessary roughing and a finishing
pass(es). For parts produced using EDM, he reads the part file into
ESPRIT and uses several of the software's commands to convert the solid
geometry into x, y and u, v coordinate data that drives a wire EDM
machine. Next, the operator gives the software other information about
the job such as power settings, flushing conditions and feedrates. The
x, y and u, v planes are then lined up by means of a series of match
points around the entire contour of the part. After this step, all that
is left is to send the file through a post processor, which takes the
information that has been entered and formats the G-Code of the
toolpath for the EDM machine.
Breuil concludes that the company's ability to rapidly implement design changes had a significant impact on the excellent racing performance of the company's parts as well as its success in the commercial market. "ESPRIT gives us the ability to create new products in a fraction of the time that was needed in the past. This means that we can quickly create a new product to meet a special need of one of the top racers or take advantage of a market opportunity. Plus using an inexpensive PC rather than a costly machining center to do our programming saves a lot of money."
For more information contact DP Technology Corp. (Camarillo, CA) at (805) 388-6000 or via its website at www.dptechnology.com.
