Product introductionProduct introduction

Chains are Made with Various Processes

World quality chains are born from the high-level quality management system of Hamanaka Chain Mfg. Co., Ltd.
Below is the introduction of the manufacturing process.

Chain Manufacturing Process Outline Drawing

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BAR CUTTING Round steel bars for chains that just arrived from a steel manufacturer are cut to required lengths.
BAR HEATING They are heated to be processed into the shape of chain links. Rotation is applied while heating, so that steel is heated uniformly.
DESCALING Scales (oxides etc.) on the surface of steel bars are removed by spraying highly pressurized water.
CHAIN MAKING Long chains are manufactured by implementing the processes in the order of: BENDING → WELDING → TRIMMING → ALIGNMENT ＆ STUD SETTING → / BENDING→...
BENDING Heated steel bars are bent into the shape of chain link. During the first process workpieces are bent into the shape of the letter J, during the second process ? into the shape of a C. When being bent into the C-shape, the link is connected to the previous chain link.
FLASH BUTT WELDING We conduct flash butt welding, one of our special processes, on the end surface of a link bent into the C shape. In this process, a flash is generated at the end surface and heat is applied, then once the whole piece is in a molten state, the welding is finished by pushing the ends together. Various parameters of each link such as voltage, current, time, etc. are controlled by a computer.
TRIMMING Scraping off protruding parts (burrs) including the oxides from the welding process.
ALIGNMENT ＆ STUD SETTING Chain links are shaped into the standard size. In case of a chain with studs, studs are inserted at this time and pushed it into each link and fixed.
PRE-INSPECTION Checks for defects and flaws during the manufacturing process are carried out immediately.
STUD WELDING In case of marine chains, studs are welded to prevent them from falling out.
HEAT TREATMENT We perform vertical continuous heat treatment, which is our special process. QUENCHING and TEMPERING are done continuously by passing chain links through a vertical furnace. By making this a continuous process, it is possible to apply heat treatment of uniform quality to the entire chain. This process determines the strength and toughness of the chain, so it is a very important process.
PROOF LOAD TESTING A confirmation of the durability, under the technical standards for ship construction & operation, to the whole chain that has undergone heat treatment, to ensure no deformation & damage.
BREAK LOAD TESTING Adding weights above the proved load to some random chain samples to check whether damage occurs.
MECHANICAL TESTS Tensile test and Charpy impact test on test pieces collected from some random samples of the chain for the mechanical nature (such as strength & tenacity) of the chain
FINAL INSPECTION Visual confirmation, non-destructive tests and size measurement to all chain items underwent the proof load testing for any flaw as the final inspection.
PAINTING ＆ SHIPPING Chains that have gone through all inspections are painted and shipped.
BAR CUTTING
Round steel bars for chains that just arrived from a steel manufacturer are cut to required lengths.
BAR HEATING
They are heated to be processed into the shape of chain links. Rotation is applied while heating, so that steel is heated uniformly.
DESCALING
Scales (oxides etc.) on the surface of steel bars are removed by spraying highly pressurized water.
CHAIN MAKING
Long chains are manufactured by implementing the processes in the order of: BENDING → WELDING → TRIMMING → ALIGNMENT ＆ STUD SETTING → / BENDING→...
BENDING
Heated steel bars are bent into the shape of chain link. During the first process workpieces are bent into the shape of the letter J, during the second process ? into the shape of a C. When being bent into the C-shape, the link is connected to the previous chain link.
FLASH BUTT WELDING
We conduct flash butt welding, one of our special processes, on the end surface of a link bent into the C shape. In this process, a flash is generated at the end surface and heat is applied, then once the whole piece is in a molten state, the welding is finished by pushing the ends together. Various parameters of each link such as voltage, current, time, etc. are controlled by a computer.
TRIMMING
Scraping off protruding parts (burrs) including the oxides from the welding process.
ALIGNMENT ＆ STUD SETTING
Chain links are shaped into the standard size. In case of a chain with studs, studs are inserted at this time and pushed it into each link and fixed.
PRE-INSPECTION
Checks for defects and flaws during the manufacturing process are carried out immediately.
STUD WELDING
In case of marine chains, studs are welded to prevent them from falling out.
HEAT TREATMENT
We perform vertical continuous heat treatment, which is our special process. QUENCHING and TEMPERING are done continuously by passing chain links through a vertical furnace. By making this a continuous process, it is possible to apply heat treatment of uniform quality to the entire chain. This process determines the strength and toughness of the chain, so it is a very important process.
PROOF LOAD TESTING
A confirmation of the durability, under the technical standards for ship construction & operation, to the whole chain that has undergone heat treatment, to ensure no deformation & damage.
BREAK LOAD TESTING
Adding weights above the proved load to some random chain samples to check whether damage occurs.
MECHANICAL TESTS
Tensile test and Charpy impact test on test pieces collected from some random samples of the chain for the mechanical nature (such as strength & tenacity) of the chain
FINAL INSPECTION
Visual confirmation, non-destructive tests and size measurement to all chain items underwent the proof load testing for any flaw as the final inspection.
PAINTING ＆ SHIPPING
Chains that have gone through all inspections are painted and shipped.