CELLULAR MANUFACTURING

CELLULAR MANUFACTURING Cellular manufacturing is a process of manufacturing which is a subsection of just-in-time manufacturing and lean manufacturing encompassing group technology. The goal of cellular manufacturing is to move as quickly as possible, make a wide variety of similar products, while making as little waste as possible.

Cellular manufacturing involves the use of multiple "cells" in an assembly line fashion. Often the cells are arranged in a "U-shape" design because this allows for the overseer to move less and have the ability to more readily watch over the entire process.

Once implemented, cellular manufacturing has been said to reliably create massive gains in productivity and quality while simultaneously reducing the amount of inventory, space and lead time required to create a product. It is for this reason that the one-piece-flow cell has been called "the ultimate in lean production."[1]

Cells are created in a workplace to facilitate flow Cells are created in a workplace to facilitate flow. This is accomplished by bringing together operations (or machines, or people) involved in a processing sequence of a products natural flow and grouping them close to one another, distinct from other groups. This grouping is called a cell.

The number of workers inside these formations depend on current demand and can be modulated to increase or decrease production. For example, if a cell is normally occupied by two workers and demand is doubled, four workers should be placed in the cell. Similarly, if demand halves, one worker will occupy the cell. Since cells have a variety of differing equipment, it is therefore a requirement that any employee is skilled at multiple processes.[1]

Formation of cells consistently frees up floor space in the manufacturing/assembly environment (by having inventory only where it is absolutely required), improves safety in the work environment (due to smaller quantities of product/inventory being handled), improves moral (by imparting feelings of accomplishment and satisfaction in employees), reduces cost of inventory, and reducing inventory obsolescence.[1]

In order to implement cellular manufacturing, a number of steps must be performed. First, the parts to be made must be grouped by similarity (in design or manufacturing requirements) into families.

Then a systematic analysis of each family must be performed; typically in the form of production flow analysis (PFA) for manufacturing families, or in the examination of design/product data for design families. This analysis can be time consuming and costly, but is important because a cell needs to be created for each family of parts.

Outline of Chapter 6 Process Thinking The Process View of Business Measuring Process Flows Measuring Process Flows at Pizza U.S.A. Process Flowcharting Process-Flow Analysis as Asking Questions Business Process Reengineering (BPR)

Process Thinking Process Thinking: all work can be seen as a process Definition of a “system” Whole > sum of parts Application of systems thinking to businesses Defining system boundaries Role of “cross-functional” teams in systems analysis Systems thinking requires cross-functional teams to include all affected functions

Figure 6.1: Process View of Business

Measuring Process Flows Little’s Law Relates number of items in the system to arrival rate and length of time in the system Formula: I = T x R I = average number of things in the system T = average throughput time R = average flow rate into the process Assumes system is in a ‘steady state’

Applications of Little’s Law Manufacturing Waiting lines Invoice processing Legal office transactions Accounts receivable processing Etc.

Measuring Process Flows Capacity of a system = capacity of the most constraining resource This resource is called a ‘bottleneck.’ The flow rate of a process is the minimum of: Supply Demand Capacity

Process Flowcharting Process Flowcharting: creation of a visual diagram to describe a transformation process Also known as: Process mapping Flow-process charting Service blueprinting Value stream mapping

Process Flowcharting Purpose: to describe a process visually to find ways of improving the current process. Find repetitive operations Identify bottlenecks Describe directions and distances of flows (people, material and information) Reduce waste Required for certifications such as ISO9000

Process Flow Analysis Might Change: Raw materials Product (output) design Job design Processing steps used Management control information Equipment or tools Suppliers i.e. Anything but customers may be changed!!

Steps in process flowchart analysis using the systems approach Select a process to study Form a team to analyze & improve the system Specify the boundaries of the transformation process Identify and sequence the operational steps Identify the performance metrics Draw the flowchart

Symbols for Flow-Process Chart Operation (a task or work activity) Inspection (an inspection of the product for quantity or quality) Transportation (a movement of material from one point to another) Storage (an inventory or storage of materials awaiting the next operation) Delay (a delay in the sequence of operations)

Questions to Ask in Process-Flow Analysis & Improvement What does the customer need? What operations are necessary? Can some operations be eliminated, combined, or simplified? Who is performing the job? Can the operation be redesigned to use less skill or less labor? Can operations be combined to enrich jobs? Where is each operation conducted? Can layout be improved? When is each operation performed? Is there excessive delay or storage? Are some operations creating bottlenecks? How is the operation done? Can better methods, procedures, or equipment be used?

Questions to Ask in Process-Flow Analysis & Improvement Flow Balanced? Where is the bottleneck? Are all steps necessary? How jumbled is the flow? Time How long to produce one unit? Can it be reduced? Cycle time? Excessive set-up time? Excessive waiting time? Quantity Theoretical production amount? How easy to change? How many units actually produced? Quality Historical defect rate? Which step contributes to defect rate? Where do errors occur? Cost Cost to produce one unit? What are cost buckets for one unit? Can some of the buckets be reduced or eliminated?

Business Process Reengineering (BPR) BPR defined (Hammer and Champy, 1993) BPR Philosophy Principles of BPR Success of BPR

BPR Defined BPR is “the fundamental rethinking and radical redesign of business [or organizational] processes to achieve dramatic improvements in critical, contemporary measures of performance, such as cost, quality, service and speed.”

BPR Defined This is in contrast to incremental change or continuous improvement of an existing process. “If I were recreating this company today, given what I know and given current technology, what would it look like?”

BPR Philosophy Neither. Does the reengineering consultant see the glass as half full or half empty? Neither. It’s the wrong size of glass! Or, should it be a glass? …or a liquid?

Principles of BPR Organize around outcomes, not tasks Have the people who do the work process their own information Put the decision point where work is performed, and build control into the process Eliminate unnecessary steps in the process

The Success of BPR According to Hammer & Champy, 50-70% of organizations attempting BPR do not achieve the results they expected. Why? Because they make one or more of the 17 common mistakes (see next 2 slides):

BPR Mistakes Trying to fix a process instead of changing it Not focusing on business processes Focusing only on the process redesign Neglecting people’s values & beliefs Settling for minor results Quitting too early Constraining the scope of the problem & effort Letting corporate culture & mgmt attitudes get in the way Trying to reengineer from the bottom up

BPR Mistakes (cont.) Assigning a leader who doesn’t understand BPR Skimping on the resources Not making BPR a top corporate priority Trying to do too much at once & dissipating resources Concentrating only on design & not implementation Trying to keep everyone happy Pulling back if people resist Dragging out the effort & taking too long Source: Hammer & Champy, Reengineering the Corporation, chapter 14.

Summary Process Thinking The Process View of Business Measuring Process Flows Measuring Process Flows at Pizza U.S.A. Process Flowcharting Process-Flow Analysis as Asking Questions Business Process Reengineering (BPR)

End of Chapter Six