Waterjet Cutting Composites
Composites have unique properties that present challenges for traditional metal working facilities. At DMSI we have extensive experience working with various types of composites and are able to meet the demanding tolerances of the aerospace, automotive, prosthetic device, recreational equipment, and other industries.
Often, composite components are made to approximate sizes and then trimmed to their final size manually during assembly. This process is both time-consuming and inaccurate. With our 5-axis abrasive waterjet machines and router, DMSI can produce parts to levels of accuracy similar to metal components so that composites can achieve their full market potential.
One of the key problems with composites is that machined holes and pockets tend to be undersize because the material relaxes when it is cut. This effect is difficult to predict because it is impossible to cut all the fibers in the same orientation. Drilling through a layered composite structure is likely to push the layers ahead of it, producing unacceptable delamination on the exit side. Problematic hole entry defects are sometimes a concern as well because as the drill enters it can wind up the top layer of the composite material. With our abrasive jet technology we can eliminate these problems and hold tolerances to ± .0025”.
A conventional end mill’s hard, solid cutting edge can produce separation of the layers of material or pull-out of the carbon fibers in composites. That is why, instead of tools with edges, at DMSI we use abrasive milling tools to machine composites. We avoid these problems by using tools with high spindle speeds for an efficient abrasive machining effect. And we employ another option that achieves abrasive machining at even faster speeds. While an abrasive milling tool in a fast spindle might reach a cutting speed equivalent to about 50 miles per hour, our abrasive waterjet machines deliver the abrasive across the work piece at a speed of approximately Mach 3.
Among the main benefits aircraft manufacturers seek though machining composites with waterjet are faster cutting and avoiding damage to the work piece.. Other benefits include:
- No heat-affected zone
- No delamination
- No fiber pull-out
- No rigid clamping
- No dust
- Increased cutting speeds
- Higher-quality parts because abrasive waterjet cuts in one pass, leaving material composition and microstructure undisturbed
- Improved accuracy
- Omni-directional shape cutting capabilities, including inside corners with .020” radius
- Finished edge quality so that secondary finishing is unnecessary
- Minimized tooling
Rotary-tool machining remains useful in many composites applications and certain features must be machined in this way. While waterjet can machine a hole, for example, it cannot machine a counter bore. For such applications, our waterjet machines incorporate a 5-axis router that can be programmed with the same accuracy as the abrasive water jet cutting operation.
When Airbus was considering production of its A350 extra wide body aircraft, which are comprised of more than 50% composite materials by weight, abrasive waterjet offered a clear economic advantage. The abrasive and other consumables cost less than the conventional cutting tools and the cost of the machine time was also less because the faster cutting means the part spends less time on the machine. They said, “This was the best economical approach considering both recurring and non-recurring costs.” An added bonus was the elimination of deburring operations because the machined edges are clean enough for the composite parts to be considered finished as soon as the waterjet cutting is done.
Boeing also found abrasive waterjet machining to be an excellent tool for cutting composite materials. As a non-contact cutting technique, abrasive waterjet minimizes mechanical forces on the parts, which has kept Boeing’s fixturing requirements to a minimum. Boeing achieved a tremendous amount of cost savings through the elimination of tooling and reduced setup time. Other benefits include faster production and higher quality parts due to improved accuracy and better finished edge quality.
At DMSI, we have found a niche for ourselves by efficiently machining composite parts that other, larger aerospace contractors have difficulty machining in a cost-effective way. Both high-volume and low-volume runs are practical and items up to 120” x 288” can be accommo- dated. Parts can be re-manufactured by simply re-running our computer programs.
Contact us via phone, fax, or email for a quote on your next project.