How to manufacture a connecting rod at factory ?

The journey of manufacturing a forged connecting rod begins with a forged blank,the blank shaped from a die .

The first process is machining the rod blank roughly, includes mill and grind the big end and pin surface , drill the pin bore hole .

The second process is contouring the beam shape , roughing the surface to be like a mirror . At this time, the oxide layer or rust covering on the blank’s surface is completely removed.

To remove the source of potential stress fractures on the connecting rods, the connecting rods need to be polished, the polishing process can help to improve connecting rods durability and decrease rod weight, and further remove the burrs and flashes in the rods .

The next process is shot peen, which can help to eliminate residual stress inside steel structures and remove flash projection, burrs, chopping and prevent connecting rod fatigue failures, it is a indispensable connecting rods manufacturing process .

After serial number engraved on the rod cap and beam , we will use cutting machine to split the connecting rod.

Since the beam and cap have been separated, in order to catch the crankshaft tightly, the connecting rods need support from fasteners, so big end holes will be drilled and threads must be processed in the big end hole .

Then the dowel sleeve will be pressed into both ends of big end ,this guarantees that when the rod is assembled and the bolts pre-loaded, the big end bore should take the same form as it did immediately after final machining.

Similarly, the copper bushing need to be pressed into pin end too, the bushings provide a low-friction interface between the connecting rod and the crankshaft, ensuring smooth power transfer and minimizing wear on essential engine components to extend engine life. At the same time , they will help to improve efficiency and reduce vibration and noise .

After the dowel and copper bushings pressed well, the rods will be assembled customized temporary rod bolts which will fasten big end cap and beam together. The temporary rod bolts is different with standard bolts , they are customized , and more harder and longer .

And then the oil hole will be finished in the small end floating pins, allowing oil to enter the small end for lubrication . There are two methods of pin oiling: one hole drilled from the top down, or two drilled on each side from the bottom up,but there is no consensus on which is better .

We are going to continue precision machining process now, in these process, we will fine finish big end bore, small end bore, drop surface of small end and big end, guarantee every rod produced within established tolerances.

The next step is milling bearing locators to fix connecting rod bearings.

To reach customer's exact specifications, we will hone connecting rods which is a machining process to get super finishing of big end bore and small end bore.

After completing the rough machining processes, our QC team will use threads gage to check bolt hole , to ensure per rod threads pass through specific threads and prevent dust and maintain standard torque.

Then we do operations with cleanliness, to guarantee per rod free of debris, residual abrasive material, and corrosion products . It is also convenient for weighing, ensure the rod weight is not disturbed by impurities.

The purpose of weighing is to gather 4pcs/set , 6pcs/set and 8pcs/set connecting rods with closest weight into one group, so that the weight difference between the connecting rods in a same group is the smallest.

After checking and inspecting different dimensions like centre C/C length, bores diameter, width, thickness, roundness, roughness etc . The final process is packaging, proper care for rust prevention will be did, anti-rust oil will be applied on each connecting rod, each connecting rod will be covering with anti-rust paper, packing by independent packaging bags and boxes, to be ready and delivery to users.

So far , the entire connecting rod manufacturing processing is completely done. We may not show all operations details in here , if you are interested in more , please feel free to write to us via sales@keomit.com.