Wednesday, August 15, 2012

Metal Stamping Process

Metal stamping processes use dies and punches to cut the metal into the required shape. The male components are called punches and the female components are called dies.

Press machine tools are used in the stamping process. The die, made of hardened steel, has a contour that matches the shape of the finished part and is mounted on the table of the press.

The punch, made of hardened tool steel or carbide, also matches the contour of the part but is slightly smaller to allow clearance between the die and the punch. It is mounted in the head or RAM, which moves down and punches the metal. The thickness of the sheet metal does not change during this process.

Design and manufacturing of dies and punches is a highly skilled process. Master craftsmen use precision jig boring, grinding, EDM, and lapping machines to produce highly accurate dies. Progressive stamping is used to design complex profiles. In this process, the profile is cut in steps with a series of different sized die and punch combinations. 

The first punch in the series cuts a smaller profile and the next punch finely polishes the metal to obtain a desired shape. Tumbling process or deburring is used to remove any sharp edges and burrs. All through the process it is important to maintain a minimum wall thickness for the punched hole.
The metal may be plated with palladium, nickel or tin to protect it from oxidization. 

Plating improves the durability and solderability of the product. For additional shelf life, the sheet metal is also pre-plated before the actual stamping process. The product is then cleaned to dispose of excess oils, grease, films or other materials used during the stamping process. 

The heating process follows the cleaning process to enhance the toughness of the metal product. In some cases, to ease the stamping process, the sheet metal is subjected to a stress relieving process that removes internal stresses in the sheet and improves its machineablity.


Metal Stamping Definition

Metal stamping is a process employed in manufacturing metal parts with a specific design.

A metal alloy sheet is used as the stock. This stock is either stamped on a press using dies and punches or drawn into shapes on hydraulic deep drawing machines. Common examples are sheet metal machines, automobile parts, metal components used in audio and video devices, aerosol spray cans, and even military tanks. A household example is the use of sheets of metal to make pots and pans.

Sheet metal can be molded into different pre-determined shapes. The metal must be malleable and needs to flow easily in order to be drawn into shapes. 

Stamping can be done on metals like Aluminum, Zinc, Steel, Nickel, Bronze, Copper and other alloys.

This is a mass production, economical process with low cycle time. Hence, it is widely used in manufacturing large volume products with semi-skilled labour. The process is also called chipless manufacturing.


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Commonly Used Metal Stamping Die Types

Commonly Used Type of Dies
The following dies can process various materials such as metal, plastics, paper, etc.. Materials can come in a form of sheet, strip or coil. They can be shaped, like tubing, extrusions, channels, etc.

Blanking Dies, Single Step or Progressive
• Blanking
• Piercing
• Lancing
• Shearing or cut off
• Trimming
• Shaving
• Compound
• Fine blanking

Forming Dies
• Forming, bending/with hard tooling
• Rubber forming
• Hydro forming
• Explosion forming
• Curling
• Coining
• Embossing
• Extruding
• Bulging
• Swaging
• Drawing/deep drawing

Progressive Dies or Combination of 
Some of the Above
Progressive dies are usually built for automated lines where there is no, or minimum operator input required.

Miscellaneous Dies
• Steel rule die
• Rotary die
• Side CAM die

Blanking and Forming Dies 
Can be used for both low, medium or high volume production, using different type of power sources such as:

• Hand powered
• Mechanical
• Hydraulic
• Pneumatic
• Electric

The above can be manually operated or demi or fully automated and PLC controlled.

The type of tooling and method is determined by a combination of factors, such as volume of production, available facility, budget and other resources.


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Tuesday, August 14, 2012

High Precision Blanking Tool Design


Special products require special tooling and design. Blanking thin foil type material is a challenge of its own. E.g., a 0.002 - 0.005 thickness stock to be blanked requires such small amount of cutting clearance that it is a very difficult task for most tool makers and for the equipment to do properly.

For this particular design the finished blank was made of three layers. There were two carbon film layers of 0.003 thick with a copper foil between 0.0005 thickness. The requirements were the following:

1. The part must be perfect, have no bur at all.
2. Part is rejected if the carbon chips off from the metal.
3. Part is rejected if the carbon is separated from the metal at any given area.

The customer provided samples, made by others that did not meet the request and were then rejected.

• The above criteria was achieved by using the right amount of cutting clearance for the design that this particular material needed.
• To avoid separation of the layers, the blank must have the least amount of flexing.
• To eliminate chipping of the brittle carbon layers that were only semi bonded to the copper were another challenge.
• A gentle even holding pressure was required to hold the material while it was blanked, while reducing the travel distance of the blank inside the die cavity.

To accommodate all of the above, the tool had to be well guided, with low impact movement with no vibration or sudden shocks.

The part was to be handled by lab technicians so the tool could be built for this "Clean Room" environment.

The result was excellent as expected, and the parts came out perfect.

The combination of a good design and precision tool making was the key to this success.


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Monday, August 13, 2012

Tool and Die Design


35 years of tool making and tool design experience combined with the use of SolidWorks 3D CAD software, ensure that all tools or equipment designed by Vortool Manufacturing Ltd. will perform correctly.

Vortool Manufacturing Ltd. specializes in designing tools that are used in the most extreme situations.

There have been many projects finished with absolute success that other companies have failed or rejected.

The high tech industry has a demand for parts with one of the highest quality. Some of the components are made of very thin multiple layers of different materials.


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