Die forging is also referred to as drop forging. In this forging procedure, the facility hammer is lifted and dropped on the workpiece to deform it to suit into the form of the die. There are two types of die/drop forging – open die forging and closed die (impression-die forging) forging. Both types of die forging are distinguished by the shape of the die.
This article will be reviewing the types of die forging and their pros and cons
Types of Die Forging
1. Open die forging
Open die forging is a type of forging where the workpiece or metal blank are deformed to the preferred shape with the aid of dies (the surfaces in contact with the workpiece) which do not enclose the material completely. In this open die forging, the die is either attached to the hammer or the hammer functions as the die.
Open die forging can be worked into a variety of shapes such as cylinders, discs, plates, rounds, sleeves, flat, hub, shaft, blocks, hexes, and custom-made shapes. It is used for custom work and art smithing hence the name ‘smith forging’. Open die forging is commonly used to shape steels, metals, or alloy steels but can also be used to shape nickel, copper, and titanium alloys.
Benefits of open die forging
There are several benefits of open die forging, a number of them are;
- Open die forging can be used to produce complex shapes in large quantities.
- It can be used to produce large parts weighing up to 136 metric tonnes.
- Parts produced with open die forging often have greater strength
- Reduced waste of materials
- The products often have continuous grain flow, fine grain size, and enhanced microstructure.
The main disadvantage of open die forging is that the workpiece must continuously be in motion while it is worked on. Therefore, only skilled operators can use it.
2. Closed die forging (impression-die forging)
Closed die forging is a forging process where the dies containing a previously cut profile of the preferred part move towards each other and completely or partially cover the workpiece. It is a metal forming process for small precision parts. The raw material which is about the size and shape of the final forged part is heated and placed in the bottom die. The desired shape is placed as a mirror image in the bottom or top die.
A variety of materials can be forged using close die forging. Some of them include aluminum alloys, copper alloy, nickel alloy, carbon and steel alloy, molybdenum and molybdenum alloy, stainless steel, titanium and titanium alloys, etc.
Benefits of close die forging
There are several benefits of close die forging but some of them are,
- Closed die forging impressions are more steady and accurate.
- It can generate near-net sizes and shapes.
- It has a neater and better surface finish.
- Closed die forging does require less machining and the process can be automated.
- Closed die forgings can be applied across mechanical industries.
Some of the downsides of close die forging are size and shape limitation and high tooling cost, especially for a short production run.
Open and closed die forging is unique mechanical procedures and they and serve different purposes. The procedure you choose to use depends on your expected results.