Our piston division manufactures large bore pistons – up to 540 mm bore size made of aluminum or steel – for industrial applications. At our facility we manufacture pistons for all existing large bore engines; we also manufacture custom design pistons. In addition to mono-block aluminum pistons, we manufacture pistons with aluminum bottom and steel or iron top. For pistons that require special coating, we also do nitride and phosphate coating in house; and if any other type of coating is required we outsource it from our reliable subcontractors.
Large bore piston production demands more scrutiny as the engines within these size scales are very expensive. At our piston production facilities, machining is completed using modern NC and CNC equipment. At every stage of manufacturing, each piston goes through various tests before being approved by our quality control department.
Our testing procedure includes material chemical analysis, casting micro structure control, universal hardness testing, micro hardness testing, hardness depth control and ultrasonic alpine bonding tests. This in depth procedure enables us to achieve the same quality and machining accuracy for each piston.
Aluminum pistons are casted from various compositions of aluminum alloys. They are light and their material composition enables an ideal thermal conductivity. Depending on the specific application, reinforcement parts such as cast iron ring carriers or steel parts are integrated into aluminum pistons.
Articulated (2 parts) Pistons:
Articulated pistons are manufactured for industrial applications that require more durability than aluminum pistons. These pistons consist of a steel upper section and an aluminum piston skirt. The two parts are connected with friction welding. With the steel top, these pistons are more resistant to wear and high pressure compared to aluminum pistons.
Steel (Mono-block) Pistons:
Steel pistons are made of heat and pressure resistant steel. They are specifically designed to endure high ignition pressure and high temperatures.
Piston Ring Production
Depending on the specific requirements of an industrial application we manufacture piston rings with various coatings.
Molybdenum Coated Piston Rings:For applications that require extra heat resistance, we manufacture Molybdenum-coated piston rings that offer excellent emergency running properties.
Chromium Coated Piston Rings:
Chromium coating enables extra wear resistance and durability to piston rings.
Ceramic Chromium and Diamond Coated Piston Rings:
In this coating method, piston rings are covered with chromium coating while leaving cracks to be later filled with hard materials such as ceramic or micro diamonds.
Valve – Guide – Seat Production
A Variety of valves are manufactured at GLMW valve manufacturing facilities. Valves undergo a variety of treatments such as hardening or armoring depending on the engine load and the specific industrial application. This enables extra durability and wear resistance.
Mono-Metallic ValveMono-metallic valves, as the names suggests, are made of a single material. This material is chosen based on the specific requirements of an industrial application such as high heat resistance or easy sliding.Bimetallic valveIn bimetallic valves, we combine a highly heat resistant material on top with a skirt material that can be hardened. The two materials are combined using friction welding.
The valve guide provides protection to the valve stem by absorbing lateral forces. The heat from the valve stem flows to the seat and then to the cylinder head through the valve guide. We manufacture valve guides that can resist both this lateral force and the heat.
Grey cast iron or sintered metal is used in the production of valve seat inserts. The valve seat inserts prevent the valves from colliding into the cylinder head while enabling the heat from the valves to flow to the cylinder head.
GLMW has the manufacturing capacity to produce crankshafts up to 26 tonnes in weight and 13 meters in length. Large crankshafts are manufactured based on exact design specifications. In order to completely determine all design parameters such as dimension, weight, material composition, external form, radius, oil drilling channels, surface treatment, counterweights and any other parameter that might be specific to a certain crankshaft, we work closely with our customers.
If our customer requests for manufacture of a crankshaft based on an existing new or used crankshaft, with the use of highest technology scanning machinery our technicians determine all design specifications of the crankshaft. We complete this process at our manufacturing facilities. If the circumstances require an in-situ application, then our technicians travel to the customer’s location and complete this process on site.
Forging and Heat Treatment
The primary step into the manufacturing process is the production of forgings. We use both open and closed die forging methods depending on the length of the crankshaft. Producing the forgings in house allows us to have complete control over the quality. ın the following step, each forging is applied heat treatment in order to achieve the precise material composition that is required for machining.
Surface Treatment and Hardening
Hardening of the crankshafts is the most crucial step in the manufacturing process. This is achieved by various surface treatment methods such as nitriding, stroke peening or induction hardening. These methods increase the durability of the crankshaft while enabling an increased engine output and reducing wear.
Each step of the mechanical production – interior & exterior form milling, turning, deep hole drilling, gear forming, grinding, balancing and finishing – is again completed in house in order to have full control over quality.