Two CNC routers that cost a total of $40,000 annually generate $750,000 worth of plastic display products at Artistic Plastics. The PC-controlled routers produce as many parts as five people working with hand routers. The use of these machines has lowered the labor cost of router operations, enabling Artistic Plastics to charge less for this work and win more of this type of business. The use of the CNC machines also ensures customer satisfaction by producing parts with a better surface finish than is possible to achieve with hand routers.



Artistic Plastics is a plastic fabrication company specializing in display materials for the retail industry. The company's products include items such as acrylic sign frames, jewelry holders, and chinaware stands that are used by retailers such as J.C. Penny's to display their wares. Orders range in size from 1,000 to 50,000 pieces, and Artistic Plastics normally ships about $100,000 worth of product each week. This market is very price-sensitive and typically the lowest bidder gets the job. The challenge for Artistic Plastics is to operate as efficiently as possible so that its prices are competitive while still making a profit on the job.



Ninety percent of Artistic Plastics' products consist of square pieces of plastic that are cut with saws. Because it is fast and efficient to cut straight pieces with conventional power tools, there isn't much that automation can do to improve efficiency in this area. But the remaining 15 percent of its parts, the pieces with curves, are not efficiently produced by hand. In the manual production process, operators guide a hand router along a template representing the desired shape. Typically the templates are cut from a piece of fiberboard, either by hand or with a router. The templates must accurately depict the radius of the curve, and making good templates requires patience and a skilled employee. Frequently, templates are ruined and new ones must be made before the job can continue. The other drawback to using templates and hand routers is the fact that the plastic parts must be trimmed flush to the template. This requires the operator to closely follow the template and introduces the potential for human error.


Heavy-duty requirements



In the early 1990s, company management learned about CNC (computer numeric controlled) technology and decided to try this as a way of boosting the productivity of router operations. When they began evaluating CNC routers, one requirement was uppermost in their minds. The system had to be reliable. They knew, from the volume of router work they had, that the machine would need to operate seven to eight hours a day, Monday through Friday, and sometimes continuously over three shifts when the company had a large order to fulfill. A breakdown was unacceptable because it would cause a loss of sales volume and potentially jeopardize customer relations if Artistic Plastics was late with an order. A second requirement for the CNC router was that its price was affordable. This combination of requirements ruled out a number of products on the market at the time. CNC routers that cost several hundred thousand dollars were well made but out of Artistic Plastics' price range. Those that were more affordable appeared to be made with low-end components that didn't seem like they would hold up to a large volume of work.



Then the company found the Techno Series III PC-driven CNC router from Techno, New Hyde Park, New York. This machine sold for the right price, about $18,000 at the time, and featured the heavy-duty construction Artistic Plastics required. Each Techno router is constructed from rigid and optimized extruded aluminum profiles. It has four ground and hardened steel shafts and eight re-circulating bearings in each axis. This shaft-and-bearing system produces very smooth, play-free motion and an extremely rigid system that produces high-quality cuts. It easily supports the plastic sheets that Artistic Plastics uses as well as the vacuum table the company added to quickly change setups. Another feature of the machine that contributes to its durability is the use of anti-backlash ball screws. These screws have excellent power transmission due to the rolling ball contact between the nut and screws. This type of contact ensures low friction, low wear, and long life. The ball screws also make it possible to produce parts to the machine resolution of 0.0005 inch.



The technical specifications of the Techno machine that Artistic Plastics purchased include a working area of 49 inches by 41 inches and z-axis height of 6". This router was designed for production routing and drilling on a wide variety of materials including wood, plastic, MDF, solid surfacing materials, and nonferrous metals. The price included the Mastercam CNC programming software. Although that program was originally designed for metalworking, it is ideally suited for cutting plastic because of its ability to generate the most complex contours with little programming effort.



High-volume efficiency



Once the CNC router was installed and some pieces were programmed in Mastercam, Artistic Plastics began shifting router jobs to the new machine. It performed so well that it was soon handling 95% of the router work. In fact, within the first few weeks, it had produced enough parts to pay for itself. A key feature of the Techno machine is its ability to cut 3D continuous contours at up to 200 inches per minute, far faster than most machining centers. Compared to a hand router, the Techno machine takes about the same amount of time to cut a single part. The speed advantage of the CNC approach comes when there are multiple parts to produce and several can be put on the table and cut in one operation. This really pays off on high volume jobs, when one operator can turn out as much work as five people working by hand. For example, to produce an order of 50,000 parts by hand, Artistic Plastics would have had five people working for two weeks with each producing about 1,000 parts per day. That same amount of work can be accomplished by one person running the Techno router for the same amount of time.



Because Artistic Plastics' products are visible to the public, customers insist on an excellent appearance, which includes perfectly smooth edges. This is an area where having the CNC router has also been beneficial because it can produce smoother cuts compared to a hand router. The human variability caused by having an operator closely follow a template has been replaced by a machine that never deviates from a computer-controlled path. The machine has a positioning accuracy of ±0.1 mm in 300 mm and a repeatability of 0.01 mm. The CNC router features a rapid travel rate of 200 inches per minute, a z-axis cutting force of 200 pounds maximum, 0.0005 inch resolution and repeatability, and 0.003 inches/foot absolute accuracy.



After using the original Techno router for several years, Artistic Plastics was producing many more routered pieces than it had previously. This was the result of the company's ability to produce higher quality parts for a lower price, and deliver them faster, using the CNC machine. The company then purchased a second Techno machine to keep up with the demand. That CNC router, which cost $22,000, differed from the first in that it was equipped with servo motors rather than stepper motors. The servo motor allows the new router to make even smoother cuts.



Both Techno machines are in use every day, usually for the entire day. Both have proved to be as durable and reliable as Artistic Plastics had hoped. Techno was the first low cost router manufacturer in North American and has an excellent reputation for service and support.



The two Techno routers generate about $15,000 of parts each week or $750,000 annually. Because the CNC machines provide a five-fold increase in productivity over hand routers, this income is available to Artistic Plastics at a much lower labor cost, creating an overall increase in the bottom line. With the efficiency provided by the CNC approach, Artistic Plastics is able to keep its prices as low as the competition's while ensuring that the work is done profitably.