Connecting Rod and their Manufacturing

CONNECTING ROD

The predecessor to the connecting rod is the mechanical linkage used by Roman-era watermills. The earliest known example of this linkage has been found at the late 3rd century Hierapolis sawmill in Roman Asia (modern Turkey) and the 6th century saw mills at Ephesus in Asia Minor (modern Turkey) and at Gerasa in Roman Syria. The crank and connecting rod mechanism of these machines converted the rotary motion of the waterwheel into the linear movement of the saw blades.

A connecting rod, also called a con rod, A connecting rod is an engine component that transfers motion from the piston to the crankshaft and functions as a lever arm. Connecting rods are commonly made from cast aluminum alloy and are designed to withstand dynamic stresses from combustion and piston movement. The small end of the connecting rod connects to the piston with a piston pin. The piston pin, or wrist pin, provides a pivot point between the piston and connecting rod. Spring clips, or piston pin locks, are used to hold the piston pin in place.

The big end of the connecting rod connects to the crankpin journal to provide a pivot point on the crankshaft. Connecting rods are produces as one piece or two-piece components. A rod cap is the removable section of a two-piece connecting rod that provides a bearing surface for the crankpin journal. The rod cap is attached to the connecting rod with two cap screws for installation and removal from the crankshaft.

  

 

TOP MANUFACTURERS OF CONNECTING RODS

IN PAKISTAN

·         Standard Engineering Works (Pvt) Ltd.

Standard Engineering Works (Pvt.) Limited is manufacturing for the Textile and Auto parts for more than four decades. We work with modern machinery laced with advanced technology and qualified staff. The company is ISO 9001:2000 Certified. SEW has been awarded with the manufacturing opportunity for Pakistan Ordinance Factories,

Product Line: Axle, Rod Shifter, Hub Crank, Hydraulic Lift Shaft, Connecting Rod, Pin Spring, Front Axle, Pad Spring

·         Mannan Shahid Forgings Limited

Mannan Shahid set out as a small forge shop in 1974, producing 25 tons of forgings. The vision was to have a flexible facility with a diverse manufacturing program. Today, it is the leading forging house in Pakistan. Employing the latest in CAD/CAM for design and development and CNC machines for accurate and consistent machining. It is producing quality forged and machined steel components. Certified to the ISO/TS 16949:2002 Standard, it is meeting the stringent quality requirements by successfully supplying to major automotive OEMs of Pakistan, besides exporting to the USA, Italy, England, France & Germany. heat treatment including control cooling, normalizing, hardening and tempering, Iso thermal annealing, induction hardening and carburizing.

Product Line: Crankshaft, Connecting Rod, Gear Blank, Folk Shifter, Bridge Fork, Wheel Hubs, Brake Cam, Suspension Arm, Flange, Spring Seat, Pitman Arm, Steering Knuckle, Lift Arm, Differential Cross, Spindle Assembly, Double Wheel Bracket, Maillon Poussoir, Inverted Trolley Bracket, Swing Followers, Bearing Pedestal, Forged, Heat Treated and Machined Components in Carbon and Low Alloy Steels in the weight range of 300gms to 20 kgs.

·         Kad Kam Technology (Pvt) Limited

Kad Kam Technology (Pvt) Ltd is ISO 9001:2000 certified manufacturer of steel forgings. Continuous process improvement and optimization of available resources have enabled the company to offer international quality products at competitive prices. The company has production flexibility to accept custom jobs while maintaining the required quality standards. Production line includes parts for Massey Ferguson tractors, Perkins engines, Hino busses and Honda motorcycles.

Product Line: Alloy Steel Forgings, Steel Rings, CNC Turning & Milling, Connecting Rods Assembly, Eye Bolts, Shackles, Brackets, Hooks, Yokes, Vacuum Breakers Lower Links and Flanges.

·        Alba Engineering Company

Alba Engineering Company was established in 1972.High pressure fuel injection pipes, oil pipes, brake, clutch and fuel pipes for all models of cars, tractors, trucks and power generators set are the main products. The company exercise strict quality control. Precision machining and strict quality control to meet specific requirements and specifications of the OEMs is the hallmark of Alba engineering.

Product Line: High- and Low-Pressure Fuel Injection Pipes, Hydraulic Pipes, Connecting and Throttle Rods, Oil Pipes, Brake and Fuel Pipes, High- and Low-Pressure Fuel Injection Pipes, Hydraulic Pipes, Connecting and Throttle Rods, Oil Pipes, Brake and Fuel Pipes, Door Lock Rods, Throttle control Rods, Rod Support Hood.

NAME OF MATERIALS AND THEIR PROPERTIES

MATERIALS	PROPERTIES
steel	1.      The ability to absorb high impact at the expense of durability.       2.      Lightness of steel.       3.      Good tensile and Yield strength.       4.      Good Thermal Conductivity.        Etc.
Titanium	1.      Titanium is also used for high performance engine that is a             combination with lightness and strength at very high cost.       2.      Good corrosion resistance.       3.      Stiffness, Toughness, Low Density.        Etc.
Cast Iron	Cast connecting rod used in old engines.       1.      Hardness.       2.      Brittleness.       3.      Fatigue strength.       Etc.
Aluminum alloys	1.      It’s light and can absorb high impact, but it comes at the cost        of durability.       2.      Light Weight       3.      Strength at Low Temperatures       4.      Non-magnetic.        Etc.

Manufacturing Connecting Rod in Hot Forging

A connecting rod is a shaft which connects a piston to a crank or crankshaft in a reciprocating engine. Together with the crank, it forms a simple mechanism that converts reciprocating motion into rotating motion. A connecting rod may also convert rotating motion into reciprocating motion, its original use. Earlier mechanisms, such as the chain, could only impart pulling motion. Being rigid, a connecting rod may transmit either push or pull, allowing the rod to rotate the crank through both halves of a revolution. In a few two-stroke engines the connecting rod is only required to push.

Today, the connecting rod is best known through its use in internal combustion piston engines, such as automobile engines. These are of a distinctly different design from earlier forms of connecting rod used in steam engines and steam locomotives.

Hot forged connecting rods, in particular forged connecting rods for an internal combustion engine, especially when they are made of steel, are manufactured by a process which comprises hot forging of a connecting rod rough forging, a heat treatment and a machining operation.

The hot forging includes several steps:

Step 1:- Rods are cut in to proper size from billet and length by using band saw or billet shearing machine.

Step 2:- Heating of billet into oil fire furnace up to 3 forging temperature ranges i.e. from 1240℃-1270℃ and approx. 15 different ranges of temperature.

Step 3:- Placing billet in between upper & lower die using tong and completing forging in two stages i.e. forging rolling and finishing.

Step 4:- Visual Inspection is carried out after completion of forging. 

After hot forging, it can produce connecting rod in most net shaped status with less machining operations, which is very well adapted to both small and large batches. The main advantages are:

• Good ductility
• Possibility to manufacture customized parts
• Excellent surface quality
• High formability ratios
• Decreased yield strength and thus less energy required
• Increased diffusion and thus reduced chemical inhomogeneity

The heat treatment, which may be carried out at a later stage or while the rough forging is still hot, depends especially on the grade of steel used and on the desired mechanical properties.