Computers ease production monitoring, data capture.
In Part 1 of this series (see modern casting, Aug 1990), the basic control objectives and data requirements for a foundry computer-assisted production management system were discussed. This article highlights the monitoring, data entry and implementation requirements of a foundry CAPM system.
Data collection is an onerous chore in most factories. It is repetitive, boring and prone to errors. Nevertheless, manufacturing control cannot function without effective data collection in some form, be it manual, computer assisted or fully automated.
In any production work flow process, knowing what is going on where and when is central to its success. In its simplest form, Work-In-Process monitoring involves collecting only part number, quantity produced, number scrapped and date shipped. In more sophisticated systems, other data may be needed, such as batch identity, labor, production time, reasons for scrap, etc. WIP monitoring highlights deviations from the operational plan, triggers corrective action and updates the production database.
In a computerized system form, details of all shipments must be entered listing part number, quantity and date. Specific shipping information and heat number may also be added. These shipping data can be entered in the computer which automatically prints them as necessary. Number returned and the actual reasons for returns should be entered together, e.g. simple over-deliveries or failure to meets specification.
Manual - Many foundries use manual monitoring, a system likely to remain the norm in many smaller foundries. The manually-gathered information is then typed into a computer which collects and collates the information.
Usually, a pre-printed is used by shopfloor supervisors to write details of part number, work center, amount produced and date ordered. A preprinted route card, illustrated in Fig. 1, or a work-to list can be produced by computer to facilitate entry of quantities against part numbers.
Variations of manual monitoring involve the use of computer terminals on the shop floor, either as fixed terminals or as portable hand-helds with memories capable of transferring data to a main computer.
Bar Code Scanning - Bar coding is establishing itself as a preferred method of shopfloor data collection. It is reliable, fast, accurate and can be inexpensive to produce using standard dot matrix printers. Bar coding symbols are now fairly standardized, with "Code 39" apparently the best suited to industrial applications where alphanumeric data must be encoded.
For foundry applications, one of the major opportunities to use bar codes is to imprint them on route cards that accompany each batch of castings or printing them beside individual items on a computer-printed work-to list. Bar codes allow faster data collection and remove many potential sources for human error, although they may introduce one or more errors of their own such as those caused by misaligned readers.
Real Time Monitoring - Currently the most advanced form of monitoring is to attach sensors to production machines (coreblowers, diecasting machines, high-speed molding machines, etc) so that a count signal is provided, allowing regular updating of WIP data to the computer. There are obvious limitations to this approach due to the fact that not all processes can be instrumented. There also must be a means (often human) of discriminating between real products made and non-productive operation cycles.
Foundry quality control cannot be separated from production control since both share much of the same database, but there are a number of quality-associated functions that must be highlighted: * Pattern, die, tool and gage control is achieved by storing tooling information in a computer file along with details of when and where it is to be used, so that management reports can be created as needed. * Shopfloor quality documentation can be produced by an integrated management system that can produce a variety of documents containing both product-specific and order-specific details. * Historical product or process traceability is an integral part of various quality assurance requirements. * Statistical process control of both measured and dimensionless variables is often requested. Samples of dimensions may be plotted on SPC charts and details maintained on a historical basis. Similarly, the daily number of scrap castings due to a variety of sources may be plotted on a Pareto chart and stored in the total management database for display whenever requested. Scrap cause analysis allows managers to take corrective action. Graphical analysis is particularly effective in showing production trends as Fig. 2 illustrates.
Foundries have often been poorly served in respect to information for management decision making, but with the introduction of computerized manufacturing control systems, there is little excuse for this to continue. Any foundry can now have a secure form of accurate information supplied on a timely basis, though not all recipients of information need the same type or depth of detail. Figure 3 shows the principles involved.
Upper management requires reporting with little detail on a broad range of subjects, whereas a shopfloor supervisor needs a detailed report for his area of responsibility.
A list of the most commonly used management reports includes the following. * raw material requirements * job, pattern or die status * work in process summary * late orders summary * orderbook valuation * customer orders and schedules * stock reports * process stage loads * daily/weekly profit and loss reports * president's action reports
However well designed and pertinent to its needs a foundry CAPM system is, implementation remains its most critical aspect. The following rules almost always apply: * A "packaged" CAPM system should always be used because evolved software is too difficult to support with internal staff in the long term and almost always proves unsatisfactory. * A project coordinator, often the owner/manager, must take charge to ensure that there is an individual clearly responsible for the project. If the owner/manager cannot undertake this task, a consultant can prove valuable. * A team approach to implementation is essential to emphasize that the control system involves all aspects of a company's business. Once a control system has been introduced, day-to-day operation will require two staff categories: clerical operator and system coordinator.
Operators should be secretaries or clerks, trained in general use of the system. At least two should be available to cover for absence, even if this means using a part-timer. The coordinator should be that person who normally is in contact with customers and/or who schedules manufacturing.
Foundry Control Systems
The objective of using a control system is to improve company performance and profitability by efficiently converting customer orders into paid-for deliveries.
This can be accomplished only if the coordinator receives current information from all areas (sales, shopfloor, inspection, quality control, shipping, etc). The information may then be collated, compared with the foundry's operations plan, the effects assessed and decisions confidently made as to any corrective actions needed. To achieve substantial benefits for most companies who convert to computerization, it is necessary to lose a little of the flexibility inherent in a totally manual system - effectively replacing disorganization with a planned approach to total operations.
Successfully operating a small foundry in the 1990s will depend heavily upon maximizing senior management's time and talents by relieving them from non-productive tasks. Additionally, an over-dependence on the memory and skills of one individual is unhealthy and unsystematic, leaving the foundry vulnerable in case of illness or accident.
The smallest of foundries, having fewer than 20 employees and no previous experience with CAPM, will almost certainly be served best by a system that operates as a computerized T-Card system with: * a pattern/die/product database; * order processing and work-in-process tracking; * work booking; * management information creation capability; * shipping document and invoice generation.
These are the main functions which a very small foundry is likely to need. Such a system can usually be implemented in a small company within 8-10 weeks at a software cost of $5000 or less, using an IBM-PC compatible microcomputer costing under $3000. Software often can be purchased by mail-order, and the hardware is universally available.
Larger foundries, having typically between 20-75 employees, are likely to need more sophisticated functions in a CAPM system in addition to the base system described above, Among these are: * scheduling and production program formulation; * flexible, user-generated management reports; * shop-floor/quality reports; * product traceability; * price update and recalculation.
Such facilities are readily available in a foundry CAPM package to operate on either single-user or networked computer systems. Software cost will depend upon the functions and facilities needed, but a full production scheduling and control system can be purchased for $20,000 or less. Simple-to-use CAPM systems to help with both production and quality functions are invaluable aids to profitable production and on-time deliveries.
PHOTO : Fig. 1. A route card lists the operations to be carried out on the casting and allows workers to record production.
PHOTO : Fig. 2. This scrap analysis graph makes it easy to pick out trends in production processes.
PHOTO : Fig. 3. The higher up on the management pyramid, the less detail is required in reporting, but the range of reports becomes wider.
PHOTO : Fig. 1. General components of a foundry production scheduling and control system.
PHOTO : Fig. 2. A typical data entry form for a particular pattern, listing part characteristics and WIP monitoring points.
PHOTO : Fig. 3. An overload in the molding center is seven weeks out in the shop planning horizon. Production can be rearranged and the new schedule regraphed for comparison.
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|Title Annotation:||Part 2; use of computers in metal foundries|
|Date:||Sep 1, 1990|
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