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Bending is a process by which metal can be deformed by plastically deforming the material and changing its shape. The material is stressed beyond the yield strength but below the ultimate tensile strength. The surface area of the material does not change much. Bending usually refers to deformation about one axis.
Bending is a flexible process by which many different shapes can be produced. Standard die sets are used to produce a wide variety of shapes. The material is placed on the die, and positioned in place with stops and/or gages. It is held in place with hold-downs. The upper part of the press, the ram with the appropriately shaped punch descends and forms the v-shaped bend.
Bending is done using Press Brakes. Press Brakes normally have a capacity of 20 to 200 tons to accommodate stock from 1m to 4.5m (3 feet to 15 feet). Larger and smaller presses are used for specialized applications. Programmable back gages, and multiple die sets available currently can make for a very economical process.
Air Bending is done with the punch touching the workpiece and the workpiece, not bottoming in the lower cavity. This is called air bending. As the punch is released, the workpiece ends up with less bend than that on the punch (greater included angle). This is called spring-back. The amount of spring back depends on the material, thickness, grain and temper. The spring back usually ranges from 5 to 10 degrees. Usually the same angle is used in both the punch and the die to minimize setup time. The inner radius of the bend is the same as the radius on the punch.

Bottoming or Coining is the bending process where the punch and the workpiece bottom on the die. This makes for a controlled angle with very little spring back. The tonnage required on this type of press is more than in air bending. The inner radius of the workpiece should be a minimum of 1 material thickness in the case of bottoming; and upto 0.75 material thickness, in the case of coining.

ป้ายกำกับ: Bending

The Computer Numerical Control (CNC) fabrication process offers flexible manufacturing runs without high capital expenditure dies and stamping presses. High volumes are not required to justify the use of this equipment.
Tooling is mounted on a turret which can be as little as 10 sets to as much as 100 sets. This turret is mounted on the upper part of the press, which can range in capacity from 10 tons to 100 tons in capacity.
The turret travels on lead screws, which travel in the X and Y direction and are computer controlled. Alternatively, the workpiece can travel on the lead screws, and move relative to the fixed turret. The tooling is located over the sheet metal, the punch is activated, and performs the operation, and the turret is indexed to the next location of the workpiece. After the first stage of tooling is deployed over the entire workpiece, the second stage is rotated into place and the whole process is repeated. This entire process is repeated until all the tooling positions of the turret are deployed.
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Advantages
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The process is very flexible in being able to produce many different configurations of parts due to the modular nature of the tooling employed. In most cases, most of the punches and dies are already available and they can be mixed and matched to produce a variety of configurations.
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Due to the fact that most of the tooling is "available"; the lead-time for tooling is reduced or non-existent. All that needs to be done is to schedule the work order in the production shop, after the programming of the CNC process is done.
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The quantities that can be economically made can be in the thousands depending on the complexity of the part. Simple outer contours and normal size holes will allow the use of this process for many thousands of parts. However, when the part design involves irregular outer contours or large holes requiring a long cycle time, then dedicated tooling can be justified for smaller production runs. Certain parts with tightly spaced hole patterns or slots require expensive dedicated tooling, however with the CNC turret press, these parts can be easily made using standard tooling.
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Design Considerations
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To maximize utilization of material, parts are nested as close to each other as possible. They are separated from one another by "micro-ties" which are small width strips that hold the parts together during the punching process. After punching, the parts are separated by vibrating them in a shaker. The parts are known as "shaker parts" or "shake a part". This is very cost effective since no special tooling is necessary for separating them.
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Burrs are inevitable in the stamping process. The burrs are formed on the side of the sheet metal where the punch exits. Properly maintained tools (proper die clearance and sharpening) have burrs that are less than 10 % of stock thickness. When designing parts, the burrs should be confined to areas that will not be exposed to handling and should be either folded away or otherwise shielded form the user. Otherwise, an added operation of deburring needs to be done at added cost.
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Flatness/bowing can be an issue if the hole pattern is tight, and/or where excessive material is punched out. This releases the residual stresses in the material, which causes bowing or twisting of the part. Proper use of clamping and strippers can minimize this, as can subsequent straightening operations. Recognizing which side the bow can occur can also allow some designs to accept this out of flat condition by designing features that are not sensitive to this condition.
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Edge conditions. Quite often, curves and other difficult features are produced by punching out small sections at a time. This process is called nibbling. This leads to triangular shaped features. These triangular shaped features give the edge a scalloped look. This scalloping can be pronounced if the nibbling pitch is coarse. The amount of scalloping that can be accepted is a function of tooling and product cost. Clamp marks are cosmetic in nature, and if objectionable, can be so positioned to cut them away in subsequent processing.
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Lockwashers for threads can be eliminated by forming a dome on the side opposite to the screw head. As the screw is tightened, the domed thread form locks against the male thread and prevents the screw from vibrating loose in service.
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Parts that need to be welded can be positioned very precisely using shear buttons. Shear buttons on one surface are snugly fitted inside the corresponding holes into the other surface. This allows the parts to be self-jigging and eliminate the need for fixtures and other hold-downs.
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Dimensioning. As in all part design, the designer should be aware of process strengths, weaknesses. Datums should be through hole centers rather than edges of parts. This is because edges can have tapers or roll-offs, which can skew a datum and subsequent measurement. Sound practice of tolerancing methods such as geometric dimensioning and tolerancing are appropriate for the dimensioning of these parts.
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Process Tolerances. Feature tolerances can vary from ±0.12 to ±0.38 mm (±0.005 to ±0.015 in). The program can be tweaked (a little!) to improve these numbers. Repeatability is 0.05 mm (0.002 in) as long as the machine lead screw advances only in one direction.

ป้ายกำกับ: Computer Numerical Control

There are multiple CAM programs available for generating tool paths and machining operations. Generally, people become familiar with one and stick with that. As far as selecting the right one for you, my advice is this. Most software companies have free trial. Thirty-day trials are common. Take advantage of these trial periods and test the software out. Then at the end, decide if you want to try another or stick with your best one. I would advise you try out at least three different packages.

The one you select will probably have to do with your liking the interface or finding it intuitive. Keep in mind it may work for you now. A simple to use and understand interface probably has some limitations for your designs. The very best programs are complex with many tools that give you the most control. I have found that I start with a simple program and outgrow it. At some point, I move up to the next level of software. This usually means a higher price as well.

The difference with CAM Software levels is the number of Axis the software allows for. You will see the standard types below. Think of it like this, as you add more Axis’, the more sophisticated the software must get and the more it will cost. It will also give you more flexibility though. That is the trade off, money for flexibility.

The different types of CAM Software

There are many different types of CAM Software. You will need to purchase the type that fits your machine. For example, if you have a CNC Plasma Cutter, you probably only need a 2D CAM Software version. The torch will only move in the X and Y planes. That is if you have a torch height control.

What if you have a CNC Milling Machine with X and Y axes that are powered by stepper motors? You will probably only need 2.5D CAM Software. That is because your parts will have depth.

What if you have a CNC Wood Router and it carves out three-dimensional shapes out of wood? It has three servo motors to control on the X, Y and Z-axis. Yep, you need 3D CAM Software.

What if you want to mill or carve something into a cylinder of stock material? You will need a 4th Axis CAM Software so the machine can rotate the cylinder while all the other three Axis’ are moving.

Here are the most common types of CAM Software2D CAM

2.5D CAM

3D CAM

4th Axis CAM

5th Axis CAM

Don Edge has used CNC in making some of his metal art. If you want more information on CAM Software or CAD CAM Software please go to http://www.cncinformation.com

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ป้ายกำกับ: CAM

CAD stands for Computer Aided Design or Computer Aided Drafting. CAD was developed in the early 60s. Today it is the premier way to design, develop and optimized products. People use CAD every day to design virtually every product you see. Generally, designers use CAD to design a product, and then produce prints to manufacture that product. A print is a picture of a part or assembly that is very exact. It includes the dimensions and a parts list used to manufacture a product. CAD is the use of computer based software packages that assist engineers, architects and other design professionals in their designs. CAD is the part of the main designing process and involves both software and sometimes hardware. Current software packages range from 2D vector based drafting systems to 3D solid and surface modelers.

Computer Aided Drafting software packages can generally be broken into two groups. The groups are 2-D drafting packages or 3-D drafting packages. Most all software packages are moving to 3-D design. 3-D design is really the next generation of CAD. Utilizing 3-D design, engineers can make a model of their product. They can then look over this model for any apparent defects before it is ever made.

CAD is used to design, develop and optimize products. CAD is mainly used for the engineering of models and/or drawings of components. It is also used throughout the engineering process from concept to design of products. These products can be used by end consumers or used in other products. For example, you can design a bolt in CAD, and then use it in a Sub-Assembly in a planetary, which is a part of an earth-moving machine. CAD is also used in the design of tools and machinery. Finally, it is used in the design of all types of buildings from sheds to shopping malls.

Ivan Irons runs http://www.cncinformation.com/CNCBlog/ were you can get the latest on auto cad blocks, computers aided design, and CAD Blocks.

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ป้ายกำกับ: CNC And CAD

This die is being ran in a 250 ton Danly press.

ป้ายกำกับ: Maes Tool

Maes Tool & Die one out die 250 ton press
stamping maes tool die production metal forming parts punch press mechanical

ป้ายกำกับ: mechanical

Tool and Die Designer
Moraine Park's Tool and Die Designer program provides students with the high-level manufacturing skills required in Wisconsin's evolving machine tool industry for the national and international customers it serves. Critical to the manufacturing workforce, tool and die designers design machine tools, parts, molds and stamping dies with the latest CADD (computer-aided design and drafting) software

ป้ายกำกับ: Die Designer