Factory supply 0.35mm- 50.8mm HRC50-55 light AISI304 316 430 440 stainless steel ball Used in Bearing

Raw Material Inspection

Raw material comes in wire form. Firstly, the raw material is visually inspected by quality inspectors to determine if the quality is up to the mark and if there are any defected materials. Secondly, verify the diameter and review raw material certificates.

Cold Heading

The cold heading machine cuts a specified length of the wire material into a cylindrical slugs.  After that, the two hemispherical halves of the heading die form the slug into a roughly spherical shape. This forging process is performed at room temperature and a slight amount of additive  material is used to ensure that the die cavity is completely filled. Cold heading is performed at very high pace, with an average velocity of one large ball per second. The smaller balls are headed at a speed of two to four balls per second.

Flashing

During this process, the excess material formed around the ball will be detached. The balls are passed a couple of times between two grooved cast iron plates removing small amount of excess material as they roll.

Heat Treatment

The parts are then supposed to be heat treated using quenching and tempering processes.A rotary furnace is used to make sure that all parts bear the same conditions. After the initial heat treatment, the parts are immersed in an oil reservoir. This rapid cooling (oil quenching) produces martensite, a steel phase which is characterized by high hardness and superior wear properties. Subsequent tempering operations further decreases internal stress until the bearings’ final specified hardness limit is reached.

Grinding

Grinding is performed both before and after heat treatment. Finish Grinding (also known as Hard Grinding) brings the ball closer to its final requirements. The grade of a precision metal ball is a measure of its overall precision; the lower the number, the more precise is the ball. Ball grade encompasses diameter tolerance, roundness (sphericity) and surface roughness also called surface finish. Precision ball manufacturing is a batch operation. Lot size is determined by the size of the machinery used for the grinding and lapping operations.

Lapping

Lapping is similar to grinding but has a significantly lower material removal rate. Lapping is done using two phenolic plates and a very fine abrasive slurry such as diamond dust. This final manufacturing process greatly improves surface roughness. Lapping is performed for the sake of high-precision or super-precision ball grades.

Cleaning

A cleaning operation then removes any processing fluids and residual abrasive material from the manufacturing process. Customers who ask for more stringent cleaning requirements, such as those in the fields of microelectronics, medical or food industries, can take advantage of Hartford Technologies more sophisticated cleaning options.

Visual Inspection

After the primary manufacturing process, each lot of precision steel balls undergoes multiple in-process quality control checks. A visual inspection is performed to check for defects such as rust or dirt.

Roller Gauging

Roller gauging is a 100% sorting process that separates both under-size and over-size precision steel balls. Please check out our separate video on the roller gauging process.

Quality Control

Each lot of precision balls is inspected to ensure grade requirements for diameter tolerance, roundness and surface roughness. During this process, other relevant characteristics such as hardness, and any visual requirements are also evaluated.