Soft tool

This study describes one stage of a soft tool realisation, which facilitate and improve the task of the expert for x-ray image interpretation and decision-making. We are interested by tbe first four stages of this flow chart. 

Soft tools will usually comprise a shell of reinforced epoxy tooling compound, backed or reinforced (depending on size) with concrete or other dimensionally stable material. They take about 6-8 weeks to make and have a life of about 2000 components. Costs, amortized over this number, usually amount to around 2% of product value. As an alternative, electroformed nickel tools can be used, costing about three to five times more, but giving a lifetime output of about ten times (20,000 components). 

Hydroforming is a soft tool forming process, where a liquid medium, generally water with a small percentage of added oU, is pressurized and controlled by means of a hydraulic circuit and used to deform the workpiece, either a tube or a sheet, into the final component shape. 

D printing can be quicker and less expensive than conventional machining of prototype parts or production of cast or molded parts by conventional hard or soft tooling techniques (9). 

In contrast, soft-tooling methods use a computer-controlled punch and die, or a set of punches and die, and CNC. This approach allows for rapid design changes that only require the change of a computer file. These computer files, which are often referred to as drill or punch files, contain a set of X, y coordinates and a punch number for multiple punch machines. Computer programs are used to generate these files from CAD layout programs... 

Model building, prototype construction, soft tooling, and pattern making are the key steps in product design. These stages, which are usually expensive and time consuming, often... 

FIGURE 20.1 The soft-tooling process (computer-aided manufacturing [CAM]) for PCB fabrication and... 

Design analysis and review is a refinement of the initial design review performed earlier but is the first step in the CAM (soft-tooling) process.This step focuses on the actual design data submitted for fabrication and assembly. The design analysis and review step consists of the following tasks ... 

When machining steel, it should not be forgotten that a processing of the crystals in the structure takes place, i.e., the crystals are cut, shaped, and polished. Therefore, the principle cannot be invalidated that unevenness of a surface increases the longer a soft tool will be used. 

Uncertainty can color the process-selection decision, particularly because capital investment in toohng can represent substanhal financial risk. For example, the decision may be made to produce soft tools for pressure forming for a new product where there is some queshon about volume projections. Hard tooling for injection molding would result in lower part costs, but the up-front investment in soft toohng is much smaher and defrays product risk until the uncertainty is removed. 

Tool quality can also affect the surface quality and over time, the tool itself can become porous. Replacing tools generally must be done as the wear will impact part quality to the point of rejection to most OEM standards. Tool hfe varies but 1000 parts is a common figure used to estimate lifetime tool costs. Tool cost is relatively inexpensive, since it is soft tooling. However, multiple tools are generally needed to meet OEM demands. As an example, a truck hood that is from the HSU process may need 6-10 molds to meet a demand of 10,000 units per year. All this can make for an overall expensive program. Figure 1 provides a cost comparison. 

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