5 Starting New in the Mold Design Field The only prerequisite for the beginner is some knowledge of mechanical drawing delineation, whether it is done electronically on a computer (with programs like Autocad) or on the drawing board with pencil Of course, the designer must also be familiar with some areas of basic arithmetic and trigonometry; both are required to put dimensions on the mold parts so they can be machined Some of the advantages of electronic drafting are the following: (1) Designs of entire, or portions, of earlier built molds can be easily used again by simply copying or modifying some existing design features from the program's memory, without the need for tedious redrawing (2) An up-to-date library of standard mold components and hardware can be established, which can be easily and quickly accessed and reproduced in new designs without the need for redrawing them every time they are needed (3) The quality of the drawings produced by a computer printout does not depend on the skilled hand of the designer (4) The computer permits easy transmission of designs to other locations, such as in-house manufacturing centers or manufacturers at other addresses Note the computer is only a tool to the designer; ultimately, the quality of a design depends entirely on how well the designer understands what is required and what can be made Also be aware that even the most experienced designer will not always come up with the best design on the ®rst attempt, but will try out different ideas in the course of the design job This often necessitates sketching, erasing, and redrawing part or all of the picture, which is much easier to electronically There is a saying about the difference between a draftsman and a designer: ``the draftsman uses the pencil, the designer uses the eraser.'' In the old days, the designer made his drawings on paper without much care for the Starting New in the Mold Design Field appearance of the resulting picture; it was then usually left to draftpersons to produce a good, readable drawing The important thing is the thought that goes into the design of the mold, to ensure the best possible design Different solutions are always possible to achieve the same end; in fact, all mold designers have their own ideas on how to solve certain design problems To take advantage of various ideas, and to arrive at the best mold, it is good practice for the designer, after creating a mold layout, to consult with a colleague, or to arrange a design meeting of peers to discuss the proposed design In many cases it is even better to provide two or more different layouts These alternatives should then be discussed, and the best design or a composite of the various ideas should then be agreed upon This procedure is standard practice in all major design of®ces around the world It may appear to be time-consuming, but the time (and emotions) invested in such peer critique are usually outweighed by the bene®ts of arriving at a better mold Since, in general, mold designers (especially beginners) may not be familiar with machining and assembly practices, someone who is familiar in these areas should be included at such design meetings; this prevents a design of mold parts that may be dif®cult (or even impossible) to produce economically or to put together at assembly It is also bene®cial to have someone who knows the actual molding process look at a new layout It is much less expensive to catch an error while it is still in the designing stage, than to ®nd out about it later when steel has been cut or, even worse, when the mold is completed Time and money can be saved by spending more time during the design stage to consider alternatives and to get the designer involved in the manufacturing process of the mold, than by rushing a job through the design of®ce to save a few hours there When estimating the total time to build a mold, allocate approximately 15±20% of the total time for designing and detailing, about 60±70% for machining, and 15±20% for assembling the mold (This, of course, depends on the shape of the product and the complexity of the mold.) And remember that the better the drawings are when given to the shop (or an outside source), the less time is wasted during machining and assembly of the mold