Pushrod Science: It’s All About Control

Because an engine’s valve train is critical to the transfer of energy, every valve train component is critical in controlling the motion of that energy transfer. So it follows that if one component fails – they all fail. So to ensure the success of valve train components, manufacturers have committed enormous resources to research and develop components that can withstand the ultra-high demands of high performance applications.

Today, valve train components are lighter, stronger, and more durable than ever before. And in the case of pushrods, that is certainly true. However, it’s safe to say that from one company to another, not all pushrods are created equal. Many companies offer pushrods that are often not adequate for the task.

Hi-Tech™ pushrods from COMP Cams®, on the other hand, are manufactured to the highest standards imaginable. And in both material and manufacturing process they are designed to be the best of the best for high-performance use. From beginning to end, every step in the process is highly controlled and every stage is precisely monitored for absolute accuracy, consistency and quality.

Some of the process is proprietary and therefore cannot be disclosed. However, it’s possible to provide an overview of the production method without disclosure of “classified” details.

STARTING HERE

The first step in making Hi-Tech™ Pushrods is the acquisition of raw material. The material that’s used is aircraft-grade 4130 chromemoly steel tubing. This material has long been established as the best engineered composite steel tubing available to make Hi-Tech™ Pushrods.

Tubing is acquired directly from the steel mill in what is referred to as “heat lots”. Each lot is processed in volumes of 100,000 linear feet amounts. This enormous volume means that from pushrod to pushrod there is no variation in material consistency. In addition, it’s certified to show it meets specific composition standards that have been established for high performance pushrod manufacturing. This first step sets the standard for manufacturing pushrods that will be used throughout the entire manufacturing procedure.

When certified tubing is accepted, it’s inventoried and quarantined. That’s because every heat lot is processed in isolation and all the material of each lot is used before another is processed. Every lot is processed in exactly the same manner and no two lots are combined, which assures total material control and consistency for each pushrod.

Machines like this centerless grinder are used assure consistent and accurate pushrod dimensions

IT’S ALL ABOUT CONTROL

Next comes the work of actually forming pushrods and it starts with some very important preparation. First, the tubing is cut into preliminary lengths that then move on to a proprietary automated broaching process. This highly controlled step results in precise tube lengths that are absolutely accurate for a given application.

Next, the pieces move to a grinding process. This step is necessary because the raw material comes in oversized dimensions and must be ground to achieve accurate tube wall thickness and perfect concentricity.

In the grinding process, most pushrod manufacturers use the outer diameter (OD) as the point of origin in the grinding process. However, because material from the mill may have thickness variations, grinding from the OD often results in wall thickness variation.

On the other hand, COMP Cams® Hi-Tech™ Pushrods are ground using the inner diameter (ID) as the point of origin for absolutely consistent and accurate pushrod wall thickness. Consistent and accurate wall thickness is extremely important to the reliability of the pushrods and this important method cannot be underestimated. That’s because it’s the only way to assure consistency, accuracy and precise wall dimensions for every pushrod.

PRESSING THE POINT

Next, the pieces go through a process called “swedging” (or forming) that actually makes them pushrods. Simply stated, this is a hydraulic pressure process that produces radius ends to each pushrod, resulting in a perfectly formed single-piece pushrod. The specific detail of this process is another proprietary process, but the important thing to know is that the result is a perfectly formed, radius-end, single-piece pushrod that’s absolutely accurate for its high-performance application.

When the swedging step is complete, pushrods go through a finish grinding process to make sure each pushrod is cleaned up and ready for the next step, which is the heat treat process.

Pushrods are racked in preparation for heat-treating. This seemingly simple step is really very scientific to assure that every pushrod is properly heat-treated.

HOT STUFF

Like most high performance engine components, pushrods require a heat treating step. This step enhances the pushrod strength characteristics for wear-ability and longevity. Pushrods have to be strong and hard without being brittle and the specific depth of heat treating (referred to as case depth) is decisive in achieving the specific traits needed for high-performance pushrods.

Heat treating is accomplished in what’s known as a carburizing process. In simple terms, this method introduces carbon into the heating environment, which provides surface hardness as well as and additional depth of hardness to the pushrods. The hardness that’s produced is 60+ on the Rockwell scale and arriving at this value is critical in producing the perfect pushrod characteristics for high-performance conditions.

There is no part of the heat treat process too small to monitor and analyze for absolute controlled consistency. For example, a seemingly simple part of the process of making racks in which pushrods are placed for the heat-treat process is thoroughly monitored. That’s done because the composition and correct construction of the racks can affect the consistency of a heat treat cycle. Not only are the racks analyzed but the manner in which pushrods are placed in the racks is an item of concern for the quality and consistency of the heat-treat process.

Another example of in-depth analysis is the time of day heat-treating takes place. That’s because the furnace is fired by natural gas and the volume of gas supplied to the furnace has been known to fluctuate in peak hours. This seeming simple detail has been proven to be critical in the producing consistent pushrod hardness, because uneven heating due to fluctuating gas volume can produce inconsistent pushrod hardness. So the heat-treat process occurs during hours when the gas volume is known to be stable.

These examples serve as illustration that every possible measure is taken to assure that each step in making COMP® Pushrods is analyzed and monitored to guarantee the best and most consistent is made. And when the heat treat cycle is complete, sample pushrods are selected from each batch for analysis to certify the process. This analysis is conducted using highly advanced scientific equipment and includes both hardness and destructive testing to certify heat-treat integrity. When testing is complete, pushrods go to the final production operations.

At this point, pushrods are polished and a coating of black oxide is applied. Both of these steps provide a final high-tech finish before they go to the final production step.

Because of the effects of heat-treating, some warping can occur and checking each pushrod for straightness is the final production step to make sure pushrods are within very strict tolerances. It is a precise computerized process and as each pushrod is analyzed, adjustments are made to make each pushrod to assure straightness.

With all the production steps completed, pushrods are packaged and ready to go!

As you can see, this process is highly detailed and controlled to produce the highest quality and durable pushrod possible. Every step in the process is held to precise standards so that every pushrod is the best piece possible within today’s cutting-edge technology.

Although COMP® Pushrods are superior in every way, engineers are never satisfied. R&D continues in the quest of making them better. And when there’s a way to improve pushrods, COMP Cams® will be first at making it happen.

When pushrods are nearing the end of the manufacturing process, this equipment is used to make sure each pushrod is held
within strict tolerances for straightness.

It is fact that engineering and design are vital in the equation of making any superior product. But it’s also true that without the right equipment to produce a product, all the design and engineering in the world would be wasted.

And in the case of making COMP® Pushrods, every single phase of manufacturing is accomplished using state-of-the-art machinery. Not only is the equipment the best, each machine and supporting tooling is maintained to exacting standards and specifications. What that means is you can have confidence that every COMP® Pushrod is the best, most accurate and finest piece possible.

For more information on all COMP Cams® products, go to www.compcams.com or call 1-800-999-0853.

COMP Cams®
3406 Democrat Road
Memphis TN 38118