A One-Shot Deal
Think all media compositions are all the same? Guess again. "One of the problems of ceramic media is that if it is not dense enough, it won't dimple the surface, instead it will shatter as it contacts the metal surface, often causing the media to become embedded into the surface metal," says Clarke. For those who prefer glass-beading they will come to shocking terms knowing this type of fractured media will inevitably cause undesirable surface scratches. WPC ceramic media is extremely dense in comparison to media found on the market throughout the U.S. and is approximately 20 times smaller as well.
Solid lubricants such as tin, molybdenum disulfide, or tungsten disulfide can be utilized as media in the WPC process to embed them into the product surface. WPC uses various hardness alloys in addition to ceramic for various applications ranging from dry lubricants to numerous types of media. With over 10 years of metal-treatment experience, perfecting the art has enabled the experts at WPC to build a substantial reference table for different compounds and the media needed to get the desired results.
How Does WPC Treat Pistons and Crankshafts?
Pistons go through a two-stage process during the WPC treatment. The first stage is a low-density, high-impact velocity ceramic compound, which allows WPC engineers to work with soft aluminum products to get the desired application of compressive stress without distorting the component. This also allows WPC to create suitable depth micro dimples on the surface, which are essential for lubricant retention on high-sliding contact areas such as the piston skirt.
The second, and final, stage in the process is an alloy treatment used to embed a solid lubricant into the surface of the metal. This lubricant acts as a contact inhibitor. This allows the piston to slide freely, reducing contact scuffing (micro seizing) between the piston and the cylinder wall.
With a crankshaft, the process is again a two-step procedure similar to the piston scenario. The first stage requires masking off the journals and rotational sliding surfaces, which must be protected from the initial media projected onto the surface. Once all the necessary areas have been masked, WPC begins the treatment on the lobes and pin-lobe collars with a high-impact-velocity alloy media. This imparts a high layer of compressive stress onto the part and also hardens the surface at the same time.
"As the alloy is being blasted toward the surface of the crankshaft it is effectively attempting to improve the surface layer by removing any minor surface imperfections such as micro pores and surface fractures," states Ogawa. The next stage of treatment for the crankshaft is to treat the main and rod journals. "For this process, WPC uses one of our harder ceramic compounds to create fine dimples onto the surface. Once these have been treated we apply the ceramic media blast to the whole crankshaft, further improving the surface finish of the unit," states Clarke.
The Final Outcome
Surface hardness, compressive stress, and overall durability aspects are just a few of the key points associated with the WPC treatment. It's these very key elements that have made WPC Japan's most recognizable treatment among many of the top motorsports manufactures such as HKS, Suzuki Sports, TRD and Tomei Powered. An influx of these performance shops has begun selling their products with optional WPC treatment over the past few years. Even the big-dog corporations like Honda Genuine Parts and Yamaha have embraced the WPC treatment as mass-production pistons used for their vehicles utilize the WPC treatment on the side skirts to maximize longevity and increase engine efficiency.
Vehicles campaigning in sanctioned events such as "One Make Race," which forbids any internal modifications of the engine, have been known to use the WPC treatment although illegal in their class. "It's a simple 'don't ask don't tell' process when race teams or competitors send their parts to treat. We turn the blind eye and simply perform the process and ship the products back. Some teams (which shall remain anonymous) request us to treat small areas or sections on pistons or cranks that might be overlooked when an engine is being torn down after a race. They sometimes use a special chemical in an attempt to mask the area treated by WPC to make it look less conspicuous. Whatever the case might be we don't ask questions. Were just simply a treatment company," says a smiling Ogawa.