Happy’s Essential Skills: CIM and Automation Planning, Part 2—Six Principles of Automation

Estimated reading time: 17 minutes

Compatibility: the coexistence of automation and manual techniques

One of the simple truths in automation is "If you can't do it manually, what makes you think you will do it by automation," and the corollary, "automate for quality" is a myth. Automate for consistency, either consistent quality or consistent scrap. The automated system must share the same heritage as the manual systems. The most suitable manual technique for automation is Lean (JIT) or the continuous pull production technique. It focuses on many of the following problems in a conventional material flow system:

• Excess inventories queue and safety buffer
• Extensive repair and rework

Lean Manufacturing

Lean (synchronized) manufacturing is a logistics approach designed to result in minimum inventory by having material arrive at each operation just in time to be used.

Orders in a Lean system are pulled through the system by demand. They are often triggered by a reorder point system called "kanban." Every time a container of parts or materials is issued, the item is immediately ordered.

Lean applies to job shop, batch, and assembly line manufacturing but is most common in high volume, repetitive processes where a common product is being manufactured. The Lean approach reduces inventory or buffers of all types to a point where it cannot hide problems like unsuitable materials, late deliveries, or inconsistent processes. LEAN forces a business to stop the line and fix the problem before rework is created. LEAN implies changing the physical process and plant layout to reduce transit time and therefore cost and buffers. Again this shares a common philosophy with Grouped Flow Manufacturing Cells and TQC. TQC must exist within any business considering implementing LEAN. The TQC methodology must be applied everywhere by top management, even to developing a strong supplier relationship and maintenance program.

The payback of a TQC/LEAN program are real savings in dollars! Higher quality is achieved, lower inventories, work-in- process inventory tracking is no longer essential, space is reduced, equipment utilization is higher, and labor cost of all types (direct and indirect) is lower.

Automation Methodology

An automation methodology is a formal procedure for planning, designing, and implementing automation. It is particularly important when you want to start integrating several previously independent production tasks into one or more automated systems. The methodology stems from the previously defined Automation Matrix (Figure 6). Additional axes are added to the matrix to cover material handling (mechanization) between cells or work centers and to cover network communication (systemization) between cells or work centers. A simplified diagram is illustrated in Figure 8. The actual methodology will take up several drawing and utilize a number of worksheets to analyze and plan the data.

This methodology was used to design the automated printed circuit facilities for Hewlett-Packard in Sunnyvale, Palo Alto, Loveland, Boise, Boeblingen and Puerto Rico. The Automation (CIM) Information Flow Diagram^[8] from the referenced paper is shown in Figure 9. The complexity of the automation was enormously simplified by this methodology.

Figure 8: The Automation Methodology consists of automation plans for each WorkCentre plus plans for material flow and information flow between work centers.

Figure 9: The Automation Information Flow Diagram shows the major items of information transferred between customers and the internal work centers of modern printed circuit manufacturing.

Manufacturability: automation supported by product evolution

The majority of printed circuit boards are not designed by the one who fabricates them. It is very difficult then to change the design of a printed circuit. The feedback to the designers of printed circuits can then take one or more of these three common responses to the design:

1. A printed circuit unsuited to the automated systems of the fabricator will usually have quoted a higher price than ones ideally suited. This has the tendency to send the buyer elsewhere, therefore selecting the products the automated systems will handle.
2. Computer-aided tooling/artwork systems are used to process/methodize PC artwork files, put them on grid, clean up line spacing and straightness, align layers, standardize tooling and provides NC and AOI programs. They also can design the multiple image panels. All of these tasks are changing and improving the product. The printed circuit and its panel are evolving, all of which will improve the performance of the automated system.
3. Design for Manufacturing programs can be undertaken by customer or product engineering. These programs all seek to have the customer do a better job in designing the product or making changes or edits that somehow will improve the product and make corresponding cost savings.

Design for Manufacturability & Assembly (DFM/A)

Design for manufacturability and assembly is a relatively recent engineering philosophy focused on improving the fabrication of parts or simplifying the assembly of products by analyzing value, tolerance, movements, difficulty, or suitability for automation. The approach can take many avenues but the goal is the same—simplify the product and make it easier to manufacture. One technique, developed by Professors Dewhurst and Boothroyd^[9], and further refined by Hitachi and General Electric, calls for DFM/A to be based on a rigorous analysis of assembly part count, the complexity of motion and parts, and its assembly time. With this numerical rating, a more rational program of improvements is possible. See my column from June 29, 2016 for more details^[10].

Other times, the program is implemented by the customer or product engineering. It is their job to supply customers with PCB education seminars, with design/cost guidelines and tradeoff comparisons. If producing the prototypes, then a manufacturability audit or recommendations are in order. By whatever means, the goal is to have a printed circuit more producible. In our earlier comments, this will have the effect of lowering the complexity factor (C). In fact, if automation is going to be utilized, this product evolution is essential.

There are other facets of the philosophy, group technology for one, as well as value engineering, tolerance and margin analysis, analytical trouble-shooting and design of experiments. Like TQC, MRPIII and GT, DFM depends on accurate data and analysis. Again, it is the information that is important.

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