The "WPC" Process, Explained

Read an article by Mike Kojima, Engineering Editor for,
on why YOU might want to use the
WPC process on your next "build".

What is WPC?

WPC is a proven process that has been utilized for many years in the racing and automotive industry. WPC is not a coating, it is a treatment that enhances the surface to reduce friction and strengthen engine parts.

Image of WPC Treatment

WPC achieves this process by firing ultra fine particles towards the surface of a product at very high speeds. The resulting thermal discharge permanently changes the surface, strengthening structure and creating a harder more durable final product.

Media Size and Speed

Shot peening (left) and WPC (right)

Why is WPC Superior?

The WPC process is unrivalled in treating engine parts and other surfaces that have contact points of friction. WPC is superior because it is not a coating; it is a permanent surface treatment that reduces friction while strengthening the part. It's unique micro-dimple formation pattern greatly reduces friction and is unmatched by conventional methods of surface treatment.

WPC has the capacity to treat carburized, nitrided and plated parts without noticeable dimensional changes, and, upon completion of treatment, no further modifications are required of the parts. The strength and durability improvement on the surface after the WPC treatment is unsurpassed by any current methods.

Treatable products include steel, aluminum, titanium, copper and brass and soft surfaced bearings. WPC can treat any metallic item in a disassembled state.


Reduced Friction

The fine grooves, that are intrinsically engraved into the product surface at the time of machining, are transformed into micro-dimple indentations by the impact of the ultra-fine media during WPC treatment. These dimples then act as oil reservoirs.

Images of Media Blasting
Sand blasting (left), shot peening (middle) and WPC (right)

Thus, oil that would normally drain away, through the grooves in an untreated product, when pressure is applied, is instead retained in the dimples of a WPC treated product. This helps to keep the surface lubricated.

Images of Contact Area
Mirrored surface (left) and WPC treated surface (right)

Furthermore, solid lubricants such as Tin (Sn) and Molybdenum Disulfide (MoS2) can be utilized as media in the WPC process to embed them into the product surface. This reduces friction and improves the life and efficiency of the product to an even greater level.

Magnified Images of Surface Roughness

Greater Durability

The ultra-fine media of the WPC process, when projected at high velocity towards the product surface, creates compressive stress at the impact points. At the same time, a micro thermal reaction takes place. It effectively seals minor surface fractures. It also allows a condensed surface to form that has improved density due to compaction. This altered and highly compact surface condition overcomes the problem of brittleness, that is usually encountered when metals are hardened.

Benefit of Using Fine Media
Shot peening (left) and WPC (right)

The numerous impacts during the WPC process not only increase the residual compressive stress but also cause it to reside a lot closer to the surface. The cumulative result is a product that has a durability unrivalled by conventional peening methods.

  Frequently Asked Questions

Q.Will WPC Treatment change the dimensions of the parts I have treated?

A. No. The treatment doesnt add or remove material which would alter important clearances and tolerances for your parts. Strictly speaking there is a dimension change however the dimension change is almost undetectable. For example on a hardened surface such as on a crank shaft journal the dimension change will be +/- 0.00004 inches. On softer materials such as Piston Skirts and Bearings the maximum size of the dimples are less than 0.00008 inches.

Q.Does WPC Treatment improve the strength of parts as well, or is it just for friction?

A. Yes. WPC acts in two ways to strengthen parts. First it adds an extremely high level of compressive stress at and near the surface. The second point is that WPC Treatment creates a Nano - Crystalline structure at the surface of the metal. Both of these mean that metal fatigue and crack initiation are both noticeably reduced.

Q.Is the process done here in the U.S., or do I have to ship my parts to Japan?

A. WPC treatment is being done in the U.S now. We have been fully operational since Aug 2005. We promise a three day turnaround on all orders. (Some conditions apply)

Q. Do you have any minimum requirements for treating customer parts?

A. No. There is no minimum order required however we do offer discounts for people who send in more. Also we offer first time trial discounts and builder discounts to qualified builders as well.

(Visit "WPC" site to learn more, or Order...)

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