Thinking of Lean Manufacturing Systems

By Akin O. Akinlawon, Managing Director, Manufacturing Solutions/ Industrial Automation Group, Comdisco Inc.

The importance of Lean Manufacturing System is better comprehended when its impact of change on economics is thoroughly understood. The manufacturing engineering philosophy is pivoted on designing a manufacturing system that perfectly blends together the fundamentals of minimizing cost and maximizing profit. These fundamentals are Man (Labor), Material and Machines (Equipment) - called the 3Ms of manufacturing. A well balanced 3M results in

• Maximum utilization of Man - skilled and/or unskilled
• Optimal module size - cellular and/or plant
• Smooth traffic flow - of materials, man, automotive
• Minimum total manufacturing cost - of products produced
• Reduce investment
• Reduce labor requirement
• Utilization of more productive equipment
• Disposition of less productive equipment
• Flexibility to be contemporary / keep pace with market / customer changes
• Increase Return On Net Asset

There are three steps involved to accomplish the ultimate manufacturing engineering philosophy:

1. Design simple manufacturing system, commence the system design as simple as possible with low volume through the system;
2. Realize there is always room for improvements, refine the first step above as best as possible; and
3. Continuously improve the lean manufacturing system design concept with appropriate insertion of and balance of automation, conveyors and where necessary, buffer stocks.

Alternative concepts may be generated that could satisfy product and marketing technical requirements based on thorough review or re-examination of intra- and/or inter- technologies, past production process errors and lessons learned, competitive analysis, techno-communication as may be applicable. The final selection of manufacturing system concept(s) to be adopted for further consideration or development should be based upon analysis performed in conformance with established selection criteria. Let us consider two manufacturing systems that when combined give Lean Manufacturing - Flow Manufacturing System and Agile Manufacturing System.

Design Simple Manufacturing System

Flow manufacturing is a time-based process that pulls material through a production system without any interruption. This is a fundamental principle of Lean Manufacturing. This process concept can be achieved by--rapidly flowing material from raw to finished good--systematically balancing man (operator) and machine (equipment) to customer requirement.

The goal of Flow Manufacturing is to provide the ultimate response and produce to customer requirement. The benefits of this goal include:

• decreased Total Product Cycle Time,
• less inventory,
• increased productivity, and
• increased capital equipment utilization.

In Flow Manufacturing, the performance is measured by the Total Product Cycle Time (or Critical Path). Total Product Cycle Time is the longest lead time path from raw materials to finished goods. This is the quickest possible response to a customer order with finished product. Lead Time Analysis is derived from the Critical Path which enables us to highlight opportunities to reduce or eliminate NVA activities and thereby shorten the Total Cycle Product Time. By reducing the variations in the rate of flow in a manufacturing system, the lead time may be shortened. The variations can be reduce with

• random downtimes, higher uptime through quick changeover, lower downtime, etc., and
• improved quality through error proofing, self checking equipment product centered cellular layout.

Agile Manufacturing is a profitable manufacturing system that is closely related to the concept of Flow Manufacturing. It builds on the Flow Manufacturing concept to reduce lead time, optimize asset utilization and build to customer demand by focusing on being able to quickly respond to customer requests. It assumes that the customer requirement (specifications and volumes) is subject to continuous changes. A form of measurement of Agile Manufacturing performance is the program lead time.

Realize There is Always Room for Improvements

The ultimate goal is a system that has a smooth flow of material while maximizing the value added (VA) activities of the operator. Usually there are many situations in System Design Process that require special consideration. A few of these situations include:

• Manufacturing Process - is the equipment used to create, alter, assemble, measure or test the product with the objective of meeting a pre-determined product requirement. The equipment include machines, fixtures, tools, gauges such as lathes, drills, grinders, test stands and so on.

• Manufacturing System - is the combination of man and manufacturing process(es). These two are often linked together with material handling (manual or automated) to move the material or product from one manufacturing process to the next.

• Value Added (VA) - is any activity performed to a product as it moves through the production process that the customer perceived as actually adding value to the product.

• Non Value Added (NVA) - is all other activity associated with the production process that may or may not be necessary to be performed but it is nonetheless performed at present pending the emergence, awareness or availability of better methods.

Total Product Cycle Time (also known as Critical Path) is the longest lead time path from raw material(s) to finished goods. This is the quickest possible response to a customer order with a finished product. NVA activities in manufacturing system is waste. These wastes are correction, over production, movement of material, motion, waiting, inventory, and processing. Improving the flow of material through improved system layout at the customer's required rate (takt time) would reduce waste in material movement, inventory (work in progress) and improve the ability to be a JIT manufacturer. Therefore it is essential to properly apply the methodology of Lean, Flexible, Customer Focused Cellular Layout, Material Flow and Transfer, Takt Time and Operator Utilization in order to achieve the goal of Flow manufacturing and JIT.

Continuously Improve the Lean Manufacturing System Design

To be able to quickly respond to customer requirements and be a JIT manufacturer concurrently, one of the keys is to have the flexibility of equipment and have the ability to align it with product flexibility. Due to the uncertainty in customer requirement, it is important to examine manufacturing cost over a range of volumes.

Traditionally, there is a steep drop in manufacturing cost as the ideal volume requirement is approached and a steep rise as the volume is in excess of requirement. This system is generally characterized by:

• investment committed upfront, usually very high,
• more rigid and complex equipment, often not technologically modern, and
• larger capacity increments, high customer volume requirement for long period.

However, in Lean Manufacturing, the manufacturing cost does not have such a steep drop as volume requirement changes. This is because of the product flexibility and equipment flexibility that can be incorporated into the Lean Manufacturing System. This system is usually characterized by:

• investment committed as needed,
• more equipment flexibility,
• more adaptable to uncertain markets (volume / product), and
• smaller capacity increments, more product flexibility.

Lean Manufacturing System has potential for greater profit (higher RONA). The profitability depends on the utilization of its resources - the 3Ms viz

• Material moving rapidly from VA to VA operations
• Man working constantly by adding value to the product
• Machine running in a more productive manner according to customer requirement

Lean Manufacturing System can be adopted in new manufacturing system, existing manufacturing system requiring capitalization, equipment or product relocation.

Mr. Akinlawon can be reached at axakinla@comdisco.com.