The stamping technique is a manufacturing process which consists in shaping thin steel sheets named blank, thanks to a powerful drawing force. The process is based on the distortion of the surface, material that is not already stamped, with the punching method.
On this image, you can see the matrix (green part) that fits the external shape of the piece – also called « Becker »- then you can find the holding-down (blue part) that enables to hold the steel plates during the operation. It surrounds the punch that will shape the metal piece.
First of all, the steel plates is greased and put on the matrix. The holding-down is placed on the part being machined, pressurizing it, leading to the stabilization of the metal piece. Then, the punch comes to deform the metal piece by applying it against the bottom of the matrix. The steel plate gets its final shape. The punch and the holding-down can be raised.
There are two kinds of stamping process:
The hot stamping shapes the parts by heating. The steel plate and the matrix are heated to give to the part its final shape. The machining speed is lower because of the heating process that takes more time.
Hot deep drawing
We have also the cold stamping for a more precise manufacturing and at lower cost. The manufacturing is made at room temperature.
Advantages and disadvantages of the stamping process
The stamping process is an appreciated method in the industry; It is true that it enables workers to get a range of parts from thin steel plate, which is impossible to have with other processes as milling or with the use of a spin. The quality of the part is better because it is made of raw material. The polishing is cheaper and the finishing work is less demanding. The aesthetic quality of the pieces is higher than with other transformation processes. The stamping enables the manufacturing from 100 or 200 parts per hour for large volumes as car bodywork parts or from 3000 to 4000 parts for little pieces.
As we could see it before, the stamping process has already proven its worth but it also shows some weaknesses. Indeed, it requires a certain preparation time if we consider the adjustment of the tools, the punch and the matrix. These instruments, which are expensive, need a specific know-how. The matrix should be repolished not to create rips on the steel plate. Another phenomenon which creates a distortion of the piece, the withdraw of the metal piece after the punch came that it is important to relieve by waiting more time before the removal of the punch, or a mechanical stretching.
Different uses of the stamping process
This method is used in different industries, in tinplate making, for the manufacturing of tinplate utensils (basins, pots, plates etc.) but especially in the automotive industry for the design of car bodyworks and motor vehicle, for electrical household appliances also, for sanitary products as bathtub and sink and for packaging : cans and canned food.
Exapro provides you with stamping equipment as this used Sandretto press 400T, year 2008, sold at 149 000 euros.