John G. Carlson

The impact of real-time data communication on inventory management

Abstract Many current and future distribution systems cannot tolerate data capture delays found in periodic batch processing and reporting of inventory quantities, their locations and movement. The increased inventory accuracy and timeliness of real-time data permits the whole spectrum of activities of suppliers, sales and distribution personnel and customers to be performed with confidence and improved profitability. One method of real-time data collection is via bar-coding, scanning and two-way radio frequency (RF) transmission. This provides a “wireless connector” to the host computer no matter what type of items are being manufactured and/or distributed. RF systems integrate the technologies of automatic identification systems (AIS), bar-coding, automatic data capture (ADC) and enhance electronic data interchange (EDI) and quick response (QR) systems. Together with other subsystems, manufacturing and distribution firms are better able to control inventory operations and compete more effectively in servicing domestic and international customers.

Agility and mixed-model furniture production

Abstract The manufacture of upholstered furniture provides an excellent opportunity to study the impact of lot size and a comprehensive communication system on classical production management functions. The objective of this paper was to study a production system that has implemented concepts inherent in MRP, JIT and TQM while recognizing the need for agility in a somewhat complex and demanding environment. For agile production it appears essential that an on-line, real-time data capture system provide the status and location of production lots, components, subassemblies for schedule control. Current status of all material inventories and work in process is required to develop and adhere to schedules subject to frequent changes. For the large variety of styles and fabrics customers may order, the flexibility of small lots and a real-time, on-line communication system is required. Such a system can provide timely, accurate and comprehensive information for intelligent decisions with respect to the product mix, effective use of production resources and customer requirements.

Mixed model assembly simulation

Abstract Before attempting to implement JIT in low-volume, hi-tech production system it should be and can be pre-tested and aided by simulation. The volume of units for the company studied is relatively low and the cycle time per station work station is almost 30 minutes. Like so many other companies, the company looked to JIT to reduce WIP, reduce rework, reduce space, improve quality, improve customer service, be more responsive to customer needs, reduce lead time for product enhancements, reduce production cycle time and regain market share. JIT appeared as the best approach for guiding the changes necessary for reducing waste and enlisting employee cooperation. To simulate the ability of a system to achieve these benefits, the simulation package must provide a realistic and animated representation of the real system, it must be flexible to allow the experimentation and provide “snap shots” of the process data at any time. These requisites are necessary to obtain the understanding of executives and operators, to elicit their questions and suggestions and to implement the system derived from the simulations.

The role of master kits in assembly operations

Abstract In a JIT environment the production policy of having the right materials of the right quality of the right quantity available at the workstation must be operative. To ensure component availability, companies are returning to floor inventory systems which are creative, simple and cost effective, although they may appear to ignore some cost accounting principles. The procedures relevant to master kitting exemplify several MRP, JIT, FMS and group technology concepts for reducing total inventory, reducing setups and changeover time and increasing productivity, flexibility and service to customers be they inside or outside the plant or department.

Implementing just-in-time concepts into European companies

Abstract The popularity and impressive results from implementing Just-in-time concepts suggest that all repetitive and even job-shop manufacturers review the approaches and case studies. Complex mathematical models to verify a particular method of combining the production resources are not needed to yield a minimum cost product. JIT is the ultimate in employing simple concepts to the avoidance of waste and improving employee morale and dignity. Several JIT principles are reviewed in this paper which contradict traditional approaches. Nonetheless, these thought provoking ideas should be considered by those wishing to remain competitive in the domestic and world markets. Research into models which simulate various manufacturing environments must be encouraged. The growth of microcomputers, computer knowledge and computer software is permitting giant strides in our ability to test some of the controversial aspects of JIT, especially those involving economics.

A visually interactive expert system for a distribution center environment

Abstract The Warehousing and Distribution of miscellaneous case goods stored and retrieved in public or private warehousing offers an excellent opportunity to study and document rules for Storage and Retrieval systems. This study concerns the receiving, storing and shipping operations of a large Distribution Center having over 100000 storage locations for general merchandise. There are also several special storage areas for items requiring special handling such as liquids, food and fabric items, etc. The study includes developing decision rules depending on the product handled and palletizing rules depending on the case (carton) size, case quantity and weight and the stacking pattern. A preliminary study revealed that storage capacity increases of at least 4% (4000 additional pallet positions) could be achieved by optimum pallet stacking and another 5–7% by standardizing the wooden pallets themselves.

Improvement curve analysis of changeovers in JIT environments

Abstract Improvement curves are extremely useful management tools for predicting and controlling labor time and cost. This paper reviews some progress curve models and uses the log-linear improvement model to analyze the impact of product set-ups or changeover on productivity.

JIT applications to warehousing operations

Abstract The JIT philosophy has been discussed at length in the past decade and many successful applications and implementations have been made in manufacturing environments. Most of the concepts are also applicable to warehousing and distribution systems. To remain competitive, companies in this service industry must improve the quality of the services they perform and also reduce the total cost of these services. One measure of the effectiveness of the JIT applications is the reduction of errors and complaints and leads directly to higher productivity. Higher productivity is derived also from reduced picking route distance, less storage space from more frequent replenishments of smaller quantities and an administered balance and team approach among the restocking, picking, packing and loading activities.

Micro routines for demonstrating G/T, JIT, KANBAN and MRP

Abstract Of the steps necessary for successful implementation of G/T, JIT and MRP, Classification and Coding of the parts should be first. In addition to reducing design and tooling proliferation, a G/T field in the item master record is of great assistance in the operation of an MRP, JIT or conventional production control systems. With the aid of a balanced runout model and graphics, the behavior of inventory in a mixed model, JIT production system can be portrayed. Production rates, initial inventory and changeover policies are varied and the inventory levels, fluctuations, and stockouts displayed. The computation of the number of KANBANs to be cycled in a JIT system is relatively simple but often customized. A computer routine for a manufacturing firm using JIT is explained. The logic of MRP can be demonstrated with a simple, interactive routine and some illustrative exercises in a scenario or ‘what if’ format. Integrating these concepts within a production environment is a challenge for manufacturing engineers and managers.

Identifying and Controlling Coding Errors in Information Systems

Abstract Decision scientists and decision makers are often faced with a situation of uncertainty in the use of their methods and techniques when they must rely on data bases and information systems for accurate data. This paper reports on a research effort designed to change the uncertainty of the human element in the preparation of reports and data accuracy into a statement of risk in computer systems utilizing fields of coded data. Human errors in these data fields are dependent on the type of character used in the coding system, i.e., alpha, alphanumeric or all numeric, but independent of other factors commonly assumed to be causal. A methodology is presented for defining the upper limit of the probability of error in a coded data field, both before and after classical edit routines are invoked. Using this methodology, data accuracy can be treated as an element of risk rather than a factor to be pondered in the application of decision science techniques.