Chrome plated bar is a well-known and key materials for various industrial fields, this product is widely used to produce hydraulic cylinder and penumatic cylinders with honed tubing and some other accesorries. Besides cylinders, chrome plated bar can be produced to Linear shafts for various machines.
People know chrome plated bar is made of round steel bar, but what is the detailed manufacturing process? Here this article briefly describes how the chrome plated bar is produced.
Step 1. Get quality round steel bars
Round steel rods are the raw material for chrome plated rods. Usually the chrome plated bar manufacturer will buy the round steel bars from the steel makers. In China, the most famous steel makers are Xinye Steel, Baosteel, Baotou Steel, Huai Steel, Shagang Steel, Xianggang Steel and so on.
There are many different steel grades of the steel rods to make different chrome plated rods, including CK45 chrome plated bar, 1045 chrome plated bar, 4140 chrome plated bar, 42CrMo chrome plated bars, and so on.
After received the raw material steel rods, the factory need to inspect the raw material quality to ensure the raw material is with the right chemical compositiona and right mechanical properties, and ensure the materials are without any quality problems or defects, which will lead the defects on the finished product.
Step 2. Heat treated the steel bars / steel rods properly.
With suitable heat treating, the mechanical properties of the steel rods will be greatly increased. So heat treatment is very important to chrome plated bar. Normally there are two popular heat treatment process, one is Q&T (Quenching and tempering heat treatment), and the other is induction hardened heat treatment, chromed bar with this type of heat treatment is known as induction hardened chrome plated bar. However, some times the customer might will require no heat treat in the consideration of cost or some special purpose.
Step 3. Cutting the raw material round bar to fixed lengths
If the customers want the chrome plated rods are supplied with a fixed length, the factory will need to calculate the length of the raw material and cut it to length and control the tolerance on length +5/-0mm.
Step 4. Straightening the steel rods
The straightness of the steel bar is quite important during manufacturing. So before all machining, we usually need to straigthen the round steel bar first with a straightening machine.
Step 5. Peeling on the steel rods
By peeling, we could remove the Scales, Oxide, and other surface defects. This is preprocessing for grinding.
Step 6. Straightenning
Again we need to straighten the steel rods to make it ready for grinding. If the steel bar is not straight, there will be problems during grinding.
Step 7. Grinding the steel rods
Grinding the steel rods to the dimensions close to the finished dimensions.
Step 8. Straightening the ground steel rods.
Once again, we need to straighten the ground steel bars.
Step 9. The second grinding process
Grinding on the steel rods for the second time to make it precise and smooth.
Step 10. Polishing on outside diameter surface
Polish on the diameter of the steel rod to make the rod to the required dimensions and the surface condition (roughness etc), to make the steel rods ready for chrome plating.
Step 11. Chrome plating
Hard chrome plating the steel rods with a certain chrome plated thickness, such as min. 20 microns, 25 microns, … 50 microns. After hard chrome plating, the steel rods now can be called hard chrome plated shaft.
Step 12. Final polishing
Here is the finishing polishing on the chrome plated outer diameter of the steel bar, to make the surface super smoothly, the roughness can be as good as Ra 0.2 microns (10RA) or lower.
Step 13. Finished Product inspection and testing
Finally inspect the finished chrome plated rods, the inspection including dimension, straightness, surface roughness, hardness; and also we need to prepare the samples to test the chemical composition, and mechanical propterties such as yield strength, tensile strength, elongation and so on.
Step 14. Packing the finished chrome plated rods.
The finished qualified chrome plated rods need to be well packed to prevent from any damages during moving and transportation. Usually the chrome plated rods /shafts are light oiled to anti rust. And each chrome plated bar will be packed with cardboard sleeve (paper tube) to protect the outer surface. After that, they will be put into wooden cases or packed in bundles with rops wrapped for sea or rail transporationa.
Here below is the manufacturing process flow chart of the chrome plated rods.
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