Cylinder tube and chrome plated bar

Hydraulic systems & components

4th Quarter 2013 Hydraulic systems & components

Wuxi Precision Steel Tube (WPST) is entering the South African market with high quality cylinder tubing and chrome plated bar. These are the main materials used for the manufacture of hydraulic cylinders.

WPST has two cylinder tubing products: cold drawn seamless (CDS) and cold drawn welded (CDW). Cold forming increases the tensile strength of the steel, allowing an appreciable reduction in wall thickness compared to hot rolled tube. For design purposes this results in substantial weight and cost savings. The raw materials are supplied from highly reputable steel plants in China and the steel is fully killed. All tubes are subjected to heat treatment before cold drawing to produce a fine grain microstructure which prevents embrittlement and ageing. The cylinder tube is E355 (St52) grade, which also allows good weldability.

The inside H8 bore has a defect-free surface produced by honing or roller burnishing, which guarantees that seals work smoothly and precisely. Roller burnishing is a method of cold working the surface of CDS and CDW tubes to induce compressive residual stresses and produce a mirror-like finish of Ra 0,05 to 0,20 μm. The traditional honing method gives a surface Ra of 0,20 to 0,40 μm. The cross line produced on the inside surface by honing results in a residual oil deposit which lubricates the seals and prolongs seal life.

WPST has six skiving and roller burnishing machines and 45 honing machines for different size ranges (ID 32 to 300 mm, wall 3 to 25 mm) and tube lengths up to 12 metres. The company also supplies Super Smooth Inside Surface (SSID) tube by oil drawing, mainly for low pressure agricultural cylinders. Here the inside roughness is Ra 0,80 μm maximum. SSID tube is more economical than honed or burnished tube.

Hard chrome plated bar is used as piston rod material for cylinders in conditions of high stress or friction, or in harsh environments. Wear resistance, corrosion resistance, surface smoothness and uniform quality are essential properties required of hard chrome bar. WPST’s standard steel grade is CK45. The size range is from OD 6 to 220 mm with a standard length of 6 metres. Hard chrome thickness is 25 μm ±5 and the hardness is HV850 minimum. The surface finish Ra is 0,20 μm maximum. The hardening (Q&T) bar and induction hardening bar can be customised. WPST can also offer precision machining on the finished parts.

Consistent product quality is a major priority for WPST. The company aims to provide superior service with full technical and engineering support. To this end WPST is looking for a professional distributor in South Africa with warehouse facilities.

For more information contact Patrick Chu, Wuxi Precision Steel Tube Co, +86 510 8548 7111, [email protected], www.wpst.com.cn

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Cylinder tube and chrome plated bar

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