Forging Surface Cleaning Process - Blank, Before Forging, After Forging

2019-12-14 16:59:52

Why the Forging Surface Should be Cleaned?

The cleaning of forgings and blanks includes three types of cleaning: hot blanks, cold forgings or cold blanks, and partial surface defect cleaning of forgings or blanks.

forging surface cleaning process

What’s the Forging Surface Cleaning Process?

Forging blank cleaning process

In order to reduce the die wear, to prevent the scale from being pressed into the forgings, or to prevent the existing surface defects from expanding during forging, the raw materials and intermediate blanks must also be cleaned. The method of removing the local surface defects of the forging of the raw material and the intermediate blank is as follows.

After cleaning, the groove on the surface of the workpiece should be smooth, and the aspect ratio of the groove should be greater than 5.  

Scale cleaning methods before forging

There are three methods for cleaning the hot billet scale before forging:

Cleaning methods after forging

After forging or heat treatment, there are four kinds of cleaning methods widely used in production for the scale cleaning on forgings after heat treatment or after heat treatment: roller cleaning, sand blast cleaning, shot blast cleaning, and pickling.

(1)Roller cleaning

Forgings are collided or ground in rotating drums to remove scale and burrs on the workpiece. The equipment is simple and easy to use, but it is noisy. Suitable for small and medium forgings.

(2)Blast cleaning

Both blasting and shot blasting are powered by compressed air. The working pressure of sand blasting is 0.2 to 0.3 MPa, the working pressure of shot blasting is 0.5 to 0.6 MPa, and quartz sand with particles of 15 to 2 mm or steel shots with particles of 0.8 to 2 mm. It is sprayed onto the forging through a nozzle to remove the oxide scale. Generally, it is less efficient.

(3)Shot blasting

Relying on the centrifugal force of the impeller at high speed, the steel shot is projected on the forging to remove the oxide scale. Common steel shots contain 0.5% to 0.5% carbon. 7%, diameter is 0.8 ~ 2mm. Generally it is cast steel shot, wire cut shot. Shot blasting can also eliminate certain surface stress and micro-cracks while shooting down the oxide scale. And can play a strengthening role. For hardened or quenched and tempered forgings, the degree of machining strengthening is more obvious. This method has high efficiency, good effect and large noise.

(4)Pickling cleaning

The pickling fluid used for carbon steel and alloy steel forgings is sulfuric acid or hydrochloric acid. The removal of scale mainly depends on the dissolution of scale in hydrochloric acid solution. The reaction between base metal and hydrochloric acid is much slower than that between scale and hydrochloric acid. The effect of pickling and cleaning is good and the efficiency is high. However, there is greater pollution to the environment.

Anyang automatic forging line with automatic scale removal device