Made For Extreme Environments

Made For Extreme Environments





PPM Racing began manufacturing high performance 4340 and 6AL4V Titanium Connecting rods and 4340/Billet crankshafts for over 25 years and has grown to be one of the industry leaders for innovative product design. We take pride in staying ahead of the competition with the latest high tech design and manufacturing advantages. By utilising the latest in computer aided solid modeling and CNC machining centers, PPM Racing is able to offer the best designed, highest quality crankshafts, Connecting Rods and Forged Pistons available on the market today.

Traditionally, fretting between the bearing shells and big end housing is an issue with Titanium rods. Here at PPM we have developed a unique manufacturing process that eliminates this. In addition a CrN PVD coating is applied to prevent thrust face (Big End) wear.

The tremendous weight savings mean more power is passed through to the flywheel instead of expending it by thrashing heavy rods up and down. On a 300 HP engine, this can make a difference of 30 to 40 HP at high RPM — plus they are stronger and more reliable! In addition to the inherent strength of forged Titanium, these rods are also plated to totally remove any possible stress risers.

rod manufacturing


PPM connecting rods are formed from 4340 alloy steel bar. Cut into lengths, they are conveyed to an induction heater and in seconds their temperature escalates to around 2,275F.

After the hammer process, the forging is removed by conveyor belt to the hot trimmer where the flashing (the ledge of excess steel around the forging) is removed. The flashing is recycled.

One of the final operations at the forging house entails placing the connecting rods on a micro-alloy cooling conveyor that controls their hardness and mechanical properties.

This flat is also used for temporary identification marks, specifically for reuniting the rod and its cap after the parting tool makes its cut.

The next operation is to bore the small end of the connecting rod, which acts as a reliable locator for sculpting the outer profile of the cap and later for boring the big end.

Centered on the small-end bore, the forgings are fastened to a tombstone where the outer profiles of the con rod caps are machined. For strength PPM favours twin ribs between the bolt centers rather than a single rib. Note the gold-colored, carbide-tipped slotting tool used to create the twin ribs. A rounding tool contributes the finishing touches.

The parting tool with carbide-tipped blades is about to separate the rod beam from its cap.

Three engine sets of PPM connecting rods await caps to be fastened.

The next step is to machine the outside profile of the beam to size and complete the recessing operation with a ball-nose end mill, giving the I-beam or H-Beam rod its configuration. Carbide cutting tools are renewed after machining 96 rods.

“Cheeking” is the term used to center the little end in the piston, which is achieved by machining an offset on the big end. To accommodate the offset a large chamfer is also machined on the big end, which is always adjacent to the radius of the journal.

The piston pin housing is bored, honed with a cross-hatch pattern and press-fitted with an Ampco 45 aluminum nickel bronze alloy bushing. The bushing, which is initially longer than the finished size, has a .001-inch interference fit and is press-fitted into place with a 10-ton press.

After burnishing, the bushing grows around the edges; hence, it is trimmed to size and chamfered.

In a malleable, plastic condition, not a molten state, the material is handled by tongs and placed in each of three con rod impressions carved into a die block. As the hammer man runs the hammer, he displaces the soft, white hot metal into each impression, gradually forming the connecting rod. The hammer, which imposes a force of 3,000 pounds, impacts the material one strike per second. Three strikes of the hammer and the con rod is forged.

The next stage is called piercing, where material is removed from the center of the forging.

The first machining operations include face milling the big and small ends and machining a flat on one side of the big end that acts as a locator for subsequent machining operations.

Using 4340 alloy steel forgings, PPM requires a consistent hardness throughout the connecting rod and calls for a reading of 36 to 42 on the Rockwell C-scale. Testing the hardness involves pressing a steel or diamond penetrator against the surface of the connecting rod and measuring the resulting indentation.

Deburring, blending, polishing and shot blasting are all crucial operations in the making of a competition connecting rod. Here, the small end, bored to .986-inch, is being deburred.

Bolt holes are bored 3/8- or 7/16-inch. The lighter, track-tested 3/8-inch option is favoured by many of today’s racers. Because of potential deflection in the carbide drill bit, PPM drills the bolt holes on the beam separately from the caps.

After the caps are end milled, they are drilled, bored and chamfered for the locators. The machinist then interpolates and rough cuts the bore of the big end, already clamped in place behind the cutting head.

Observing the age old convention, indenting (dotting) the beam and cap confirms correct alignment of both parts. The earlier set of identification marks (on the bolt boss) have vanished during the machining processes.

Pressing home the locators

With a dial gauge micrometer measuring to the fifth decimal place, PPM measures rod width. Rod width is designed to allow two rods to be placed on a crankshaft journal, and when each rod is moved toward its journal radius, a clearance of .016-.018-inch exists between them (measured by a feeler gauge). This is called side clearance; more side clearance is preferable to less.

Roller burnishing with taper rollers squeezes the aluminum nickel bronze bushing in the small end of the rod into its bore by almost .001-inch, thus preventing the bushing from rotating under severe conditions like heat and pressure.

When honing the big end, the outer diameter of the bearings must be slightly larger than the bore of the con rod’s big end. This slight but critical difference between the two is known as bearing crush. Without bearing crush the bearings would spin in the bore. A crank pin journal of 2.100 inches requires a housing bore of 2.225 inches to accommodate the thickness of the bearings and to provide sufficient bearing-to-journal oil film clearance. Finally, each rod is checked for center-to-center accuracy before dispatch.

ppm crankshaft


The 1st process is to shape the Crankshaft  on the lathe

This process shaves the journals leaving a margin of finishing.

The next  process is to mill the pin

This process shaves the weight part coarsely, and shaves the pins leaving a margin of finishing.

The next process is to mill the weight

In order to make it the form of a crank shaft, the outside portion of weight and superfluous portion are shaved.

 Next is the Conditioning quality & shot peening

Internal stress is removed, the structure is stabilized and hardness is set to HRC 28-32.

The next process is the  2nd process to shape on the lathe

This process shaves the journals leaving a margin of polishing.

 The 2nd process to mill the pin

This process shaves the pins leaving a margin of polishing

 The oil hole, the key slot, and the bolt hole processing

This process makes the oil holes, the key slots, the pulley bolt holes, and the flywheel bolt holes.

 Next up is the pin and the journal polishing process

This process polishes the journals and the crank pins.

The dynamic balance adjustment process
In order to suppress oscillating of a crank as much as possible, the balance of a crank simple substance is measured and balance processing is performed.

 The pin and the journal wrapping process
This process is to improve the degree of true circle and surface roughness in order to gain smooth rotation and reduction of friction.

The surface treatment process
Surface strength, durability of friction, and fatigue strength of the surface is improved. The surface becomes black by the surface treatment.
  This is an  effect that helps early fitting.)

The final wrapping, bend correction, and inspection process
After the last wrapping, the bend which causes vibration is corrected. It is inspected after bend correction.

A Crankshaft is a part which receives bent vibration and twisted vibration by explosive pressure and return inertia force, therefore a crankshaft should keep its strength for corresponding these conditions. This matter should be especially needed in the tuned engine with high power. But improvement of strength becomes to decrease response of engine if to add more fat without consideration. Both strength and lightness are realized by performing stress analysis. SCM440 is used as a material and processing corresponding to the material is performed. It has both strength and lightness by giving heat treatment and a special surface treatment.

In order to rotate a crankshaft smoothly, the accuracy (The degree of a true circle, and surface roughness) of a pin journal becomes important. The crankshaft which polish finished pays careful attention to the degree of a true circle, the surface roughness, and transformation, etc.

After the finishing surface treatment, friction loss is at a minimum. Bent or out of balance crankshafts due to bad manufacturing will cause severe vibrations even with excellent counter weight balancing. Therefore Dynamic balance adjustment and bend correction are performed to eliminate as much vibration as possible.

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