(Modern Applications News - September 1998) by Richel, Inc.
Waterjet provides laser shops with another cutting process option, enabling them to compete for more contracts involving a greater diversity of materials and geometries.
Jack Budd of Precision Waterjet, a California-based job shop, is a prime example. When asked why he added a waterjet to his laser business ( and, coincidentally, changed his shop's name as well), Budd points out that even with his array of lasers he wasn't able to stay competitive in today's rapidly changing job shop environment.
With the constant development of new materials in aerospace, there is a continuing requirement to process and machine new materials. Usually these materials are able to survive exposure to high temperatures and retain their strength. Meanwhile, materials are becoming lighter, and there is a rapid increase in the use of laminated and composite materials. It is becoming more common, for example, to see a honeycomb aluminum structure 1" thick with a phenolic material laminated on the base and a sheet of stainless steel laminated on the top. In one particular instance, the presence of three completely different materials "in one" posed an interesting challenge for laser operator Joe Moretti in his New Jersey job shop. Until he expanded his shop into waterjet cutting he was forced to turn away jobs involving these materials with a no-bid comment, which is something no one wants to do.
One of the earliest to add waterjet to their lineup of services was Serge Parsadaian in the California-based laser job shop, Laser Tech. The shops business increased so dramatically that a second waterjet system was added just nine months after the first one was installed.
An analysis of the differences between laser and waterjet cutting is particularly revealing. The laser is ideally suited for cutting steel, thin stainless and nonreflective materials. The heat generated during laser cutting may cause some part damage, but in many cases this is tolerable or largely irrelevant. The maximum thickness that can be cut depends on the power of the laser, but this is generally less than 1", and tolerances can be held to 0.001" for thin materials.
Waterjet, however, can erode a path in virtually any material or combination of materials, with tolerances of about 0.005" possible for thinner materials. The maximum thickness that waterjet can cut is roughly 10" for stainless steel and 18" for aluminum, with no heat-affected zone.
Lasers are very good in their specialty area, primarily mild steels, and are capable of cutting considerably faster and with greater accuracy than waterjet. However, even differences in speed between the two processes are narrowing as cutting with multiple abrasive heads on waterjet systems enables three to six parts to be cut simultaneously. If the materials for processing are much thicker than 1", the waterjet is the obvious choice. Since the two processes complement each other so well, the combination of both services simply makes good business sense.
Shop Synergy Is The Solution
Many similarities are apparent for laser and waterjet processing, in that both make use of CAD/CAM (computer-aided design/ computer-assisted manufacturing) part information and both place the material to be cut on a cutting bed. In both cases, since parts are cut free from sheet material, provision must be made to capture the finished part to prevent damage.
For both processes, trained CNC (computer numerical control) operators were already on hand, and an established client base was ready to make use of the newly expanded services.
Another interesting observation is how job shops decide to include waterjet in their processing lineup. All three companies mentioned earlier started with lasers and considered themselves to be laser job shops. Then, they added a waterjet cutting capability later after their laser capability was established.
When asked to compare starting the laser shop with adding the waterjet, Budd (Precision Waterjet) points out that bringing in the waterjet was easier once the laser was up and running. Also, it was noted that the opportunity for larger-value contracts for waterjet cutting tends to be more numerous. For the laser, there tends to be many requests for small runs of parts for lower dollar amounts.
Although waterjet cutting is equally suited to single-part production and large part runs, it was determined that the dollar value of even smaller jobs was higher for the waterjet than for the laser. For the two processes, the hourly rate is roughly comparable. The difference is the achievable cutting speed; cutting 1/16" mild steel or stainless parts is considerably faster with a laser. However, a laser would have a difficult time cutting parts in 1/2" aluminum, if it could do the job at all.
