Custom Machinery

“Nature does nothing in vain, and more is vain when less will serve; for Nature is pleased with simplicity, and affects not the pomp of superfluous causes.”                                                                      Isaac Newton

“If it’s not designed in, it won’t break.”  Bill Lear 

Machines

Concept and Design

Machine Control

Cost and Schedule Considerations

Machines

A machine embodies functionality to solve specific problems. Its effectiveness in solving the problems depends on several factors. Some of these factors must be addressed before the machine is designed. A clear and accurate understanding of the problems and their relative priorities, a realistic appraisal of available resources, and an effectual conceptual basis are needed before an appropriate solution can be implemented. 

Today’s machine design engineers have access to tools that were not available to their predecessors of just a few decades ago. Engineered materials, fabrication methods and machine tools, scientific and technical disciplines, computers and control methodologies, and analytical instruments and procedures are but a few of the resources that are now available to machine designers. Today, it is possible to create machines with almost any desired degree of autonomy. Production machines can be engineered to address almost any problem. Production costs, product quality, production capacity, and personnel safety can all be optimized with judiciously designed machinery. 

Custom machines can perform extremely complex tasks. Cost effective assembly automation is now practical for many products that previously had to be labor intensive. Computer controlled servomotor and mechanical linkage networks can now accomplish the most demanding of tasks. Control methodologies like PID, and Fuzzy Logic (poorly named, but powerful and versatile) can now be implemented in high-level languages like C and C++ to give unprecedented levels of precision and flexibility to machine control.

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Concept and Design

A little extra time spent on concept development at the beginning of a project can save a lot of time at the end. It is wise to minimize late surprises by upfront “deep thinking”. Doing early risk analysis on functionality concepts is a prudent investment; fixing misconceptions and oversights late in a project is expensive. 

An enthusiastic rush to begin cutting metal can create the illusion of rapid progress, but the end effect can make Murphy look like an optimist. A machine’s conceptual basis is the greatest factor in determining its success. The engineer’s mental model must effectively map to reality; the laws of Nature are non-negotiable. 

A machine design begins with the engineer’s mental model (hopefully, well refined) where it exists in broad-brush strokes (mental models are the products of education, practical experience, and innate talent; not all mental models are equal). The design develops in detail during the drafting phase. Unfortunately, many good concepts are squandered during the drafting phase. Accurate mapping of the mental model to the drawing requires a close relationship between the model creator and the draftsman. For optimum results, that relationship is identity. (This principle is often vehemently denied, but never convincingly) 

Gaspard Monge developed the principles descriptive geometry early in the 19^th century. His work developed the framework for engineering drawing, as it is practiced today. Engineers now work with 3 dimensional drawings made with sophisticated Computer Aided Drafting (CAD) software based on Monge’s foundation. 

CAD permits engineers to minimize their drawing time and to thus maximize their designing time. Not only do modern CAD systems optimize communication with clients and fabrication staff, they also permit the optimization of a design, before it is built. 3 dimensional drawing is one of a machinery engineer’s most power tools. A three-dimensional CAD environment can shorten development time, improve machine quality, improve machine maintainability, improve machine performance, and make record keeping simpler and more reliable. 

Because Computer Aided Manufacturing is based on CAD, CAD drawn parts can often be made to higher quality with lower cost. CAD drawn sheet metal parts (as software) can be executed automatically by computer controlled laser cutters with high accuracy and quick turn around. CAD drawings of complex 3-D parts can be executed precisely on CNC milling machines and lathes. 

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Machine Control

A well-designed machine is an integrated system wherein the control is intimately married to the mechanical workings. This marriage must be a part of the entire design process. This means that the mechanical designers and the electrical and software designers must have a working knowledge of one another’s crafts. Too many machines seem to have been designed before the control engineer sees them; the result is usually less than optimum performance and reliability. 

Simple machines have simple controllers. Complex machines have complex controllers. PLCs using ladder logic are perhaps the most common controllers used. They are simple, rugged, and familiar. For sensing, choosing, switching, and sequencing they are excellent. More complex tasks may require more easily accessed computing power. 

Small, rugged, and extremely powerful industrial computers are now available for machine control. Though they have far more computing power than an Apollo capsule computer, and are many times faster, they are often priced less than PLCs. They offer the control power of high-level languages, like C and C++, and greater power and flexibility than can be reasonably attained with ladder logic. 

Digital PID and finely tuned Fuzzy Logic controllers can be implemented in software, increasing machine performance and reliability. Artificial Neural Networks can be implemented in software that sometimes can perform sorting functions better than trained humans. 

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Cost and Schedule Considerations

Schedules, costs, and machine features and specifications are all interrelated. You cannot expect to change one without affecting the others. Project costs and schedules can often be managed by judiciously limiting features and specifications. Production speed, degree of labor eliminated, materials specified, and a host of other factors can be varied to precisely define a project and shape it bring the best return on investment. Relaxing schedule requirements to eliminate overtime can reduce cost. Conversely, shortening a schedule may bring the added cost of overtime payments.

 While exploring a project with an engineering firm, it pays to be frank in stating your desires and concerns. By mutually exploring the options available, it is often possible to reduce project costs while still obtaining the required benefits. Machine design is an engineering specialty; it pays to make use of the firm’s expertise before setting project specifications in stone.

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