For many, `Lean manufacturing’ and `Agile manufacturing’ sound similar, but

they are different. Lean manufacturing is a response to competitive pressures

with limited resources. Agile manufacturing, on the other hand, is a response to

complexity brought about by constant change. Lean is a collection of operational

techniques focused on productive use of resources. Agility is an overall strategy

focused on thriving in an unpredictable environment. Focusing on the individual

customer, agile competition has evolved from the unilateral producer centered

customer-responsive companies inspired by the lean manufacturing refinement

of mass production to interactive producer-customer relationships.

Agility enables enterprises to thrive in an environment of continuous and

unanticipated change. It is a new, post-mass-production system for the creation

and distribution of goods and services. Agile manufacturing requires resources

that are beyond the reach of a single company. Sharing resources and

technologies among companies becomes necessary. The competitive ability of

an enterprise depends on its ability to establish proper relationships, and thus

cooperation seems to be the key to possibly complementary relationships. An

agile enterprise has the organizational flexibility to adopt for each project the

managerial vehicle that will yield the greatest competitive advantage.

Sometimes this will take the form of an internal cross-functional team with

participation from suppliers and customers. Sometimes it will take the form of

collaborative ventures with other companies, and sometimes it will take the

form of a virtual company.

Agile manufacturing is attracting an increasing amount of attention from both

the academic and industrial communities. Extensive programs are being

conducted on relevant issues to propagate agile manufacturing concepts, to

build agile enterprise prototypes, and eventually to realize an agile industry.

Why Read Lean Manufacturing?

Lean helps you to produce your business outputs as fast as possible.

The faster a business can convert a business enquiry to a finished output; then it can hold less raw material and finished stock inventory.

Holding lower inventory levels means you need less cash to run the business

Being able to produce work faster means You can do more with the same resources (machinery , people)You can complete work faster than competitors

Is reducing the cash required for your business attractive?

Lean Delivers

Lean is proven to deliver

Increased Efficiency & Productivity - 15% more output with the SAME resources (staff, machines, work space)Better Quality outputs (reducing re-work)Better on time delivery performance (stop chasing work!)Improved morale and employee engagement

What Lean Isn’t

Lean, is in our opinion, an unfortunate name for what is delivered,

Lean ISN’T

About being SKINNY

Isn’t about being MEAN

Isn’t about cutting roles

Lean Isn’t…

Lean is….

“Lean” is the set of management practices based on the Toyota Production System (TPS).

It has been applied in many sectors; engineering, manufacturing, call centres, service, legal.- This guide is for those involved in manufacturing.*

One way of defining lean is in two parts:

Eliminate WASTE and non-value-added activity (NVA) through continuous improvement.Practice respect for people.

Waste and Value Added

The opposite of waste is value-added, which has a special lean definition. An activity, in a process, is “value added ” if, and only if, these three conditions are met:

1. The customer must be willing to pay for the activity.

2. The activity must change the product, making it closer to the end product that the customer wants and will pay for

3. The activity must be done right the first time .

Respect for People - Leadership

“Respect for people” is often harder to define.

Lean leadership is about enabling and empowering people. Lean leadership is about helping people grow, allowing them to take pride in their work. Helping them and the business to continuously improve.

Lean leaders recognise how a business operates. Lean leaders set targets for people, then spend time coaching staff to meet these. They spend very little time in their office.

Lean Leaders see what is actually happening rather thanreading reports.

Why is Lean Manufacturing important?

WIPSIMPLE 3 little letters WIP or Work In Progress; WIP requires cash.A customer orders from you. You start using to cash to pay staff to process the order, to

design the parts, raw materials and sub-parts are ordered.

Employees then convert the materials and sub-parts into the required products for the

customer and these people need paying. This takes more cash - All this happens before

payment is received from the customer.

If WIP is high or rising, we’ve used up more resources

e.g. we’ve converted more cash to products that we’ve yet to finish or sell. To keep the

business running well need to get hold of more cash. In the forms of loans, overdrafts, invoice

discounting.

Bring WIP down and the amount of cash required to keep the business running comes

down.

E.g. we can reduce overdrafts, loans, finance arrangements.

How do you Reduce WIP?

Find the fastest way of getting from A to B.

If A is customer order date and B is customer delivery date then we want A to B to be a short as possible.

The shorter we can make this then the less time we have to find cash for. Normally the shortest time to produce often comes out as the least cost, so we have to find less cash as well.

Looking for the 7 Hidden Wastes

In any business there are a host of hidden wastes; these are the wastes that can’t be seen without searching them out.

Everyone can see the wasted paper, wasted materials and scrap but what about wasted time, effort, thinking, physical activity?

Lean people will try classify the “waste” in one of 7 ways.

Lean Manufacturing – 7 Wastes

Read the next few pages. If you find the examples of Waste familiar – you will benefit from Lean Manufacturing techniques.

The 7 Wastes

WaitingWaiting for design sign off and approval.

Waiting for machines to come free – waiting for maintenance & repairs to finish. Waiting for tooling changes, changeovers, or tools to be free.

Waiting for material and parts to be delivered.Waiting for quality checks.

Either the Machine or Operator is inactive during the process.

Waiting for previous jobs to finish.

The 7 Wastes

Defects and RejectsReworking errorsRe-inspection and sorting, recallsCost of Scrap and rejects

Extra labour costs (overtime) to make up production shortfalls due to poor qualityExtra transportation to remove and store rejects

Delays in process due to rejects produced

Information incorrectly recorded on job sheetsIncorrect specifications and information sheets

The 7 Wastes

InventoryThe often obvious sign of inventory waste is products made but not sold.

Sub assemblies made up but no finish dates or waiting for final build.

Batch Processing rather than single flow.

High Levels of consumables and raw materials.

Large amounts of racking and warehousing space.

The final sign is holding “production progress”or expediting meetings

The 7 Wastes

OverproductionMaking in large batches that don’t match daily, weekly, monthly demand is symptomatic of Overproduction.

Making more products or units than you can sell immediately.

Making products or units before they are required by the internal or external customer.

The 7 Wastes

Over (Extra) ProcessingToo many inspections or quality checks

Product features not requested by the customer

Excessive movement in the manufacturing process.

Large machine set-up or maintenance down time.

Bottlenecks in the manufacturing process.

The 7 Wastes

MotionSearching for tools and materials to complete work.

Handling the units more than once

Turning, Stretching, bending, reaching to do the work.

Visiting other workstations or central locations to get stock, tools, consumables etc.

Visiting other areas for paperwork, quality checks, photo copying etc.

The 7 Wastes

TransportationUnnecessary moving or handling of parts.

Handling equipment moving with no parts.

Raw material batch sizes not matching production batch size.

Materials, parts, stored a long way from point of use.

How Do We Find the 7 Wastes?

Lean people call this “GEMBA” which translated means “go to the place”.

We go to the place where work happens and watch, observe, listen – only then do we ask questions, mainly WHY?

Chapter 1Product and Process Design

1.1 Introduction

Product and process design is at the heart of all business activity and integrationwith costing enables better decisions to be made and this helps to reduce businessrisks. Such integration is still elusive and it is due to lack of a unifying method-ology. The development of such a methodology requires effective integration ofthe key variables and a user-friendly interface. Advances in computer systems andsoftware now allow us to attempt this and a research project was thereforeundertaken to study this possibility. What emerged from the effort was softwarethat proved to be of value to industry and for teaching of manufacturing engi-neering in universities. The concepts underlying this software are outlined hereand we commence by looking at the nature of product and process design.

1.2 Product and Process Design

In order to determine the manufacturing cost of a product and quickly assess a‘what if’ scenario in terms of a change at the product, part or assembly level, anintegrated perspective of product and process design is required. Such a per-spective is provided by Fig. 1.1.

1.2.1 Product Planning

Product planning remains complex due to the interactions involved between thecustomer’s requirements and the product’s functional attributes. Concepts havebeen developed to assist this process and references [1–3] highlight some of them.Product life cycle requires consideration due to shortening of product life in themarketplace and emissions requirements. It can be viewed from different

S. Grewal, Manufacturing Process Design and Costing,DOI: 10.1007/978-0-85729-091-5_1, � Springer-Verlag London Limited 2011

1

perspectives. From the manufacturer’s perspective it is the time from theconception of product to its final withdrawal from the marketplace. From themarketing perspective it is the growth, maturity and decline of sales. Fromthe customer’s perspective it is the purchase of the product to its final disposal.In reality, it is from the conception of the product to its final disposal regardless ofother stages.

Product design is broken down into its constituent parts in order to make themanufacture possible, these parts then require manufacturing and assembly. Thiscreates a number of problems and the foremost among them is the number of parts.If the number of parts can be reduced by even a small amount then the benefits

Product

Optimisation

Product Attributes Life Cycle Issues Number of Parts

Part

Optimisation

Part Attributes Task Sequence

Tooling

Assembly

Optimisation

Assembly Attributes Task Sequence

Time

Product

Product Planning

Part Planning

Assembly Planning

No

Time and Cost

Yes

Acceptable

Manufacturing System

Fig. 1.1 An integrated perspective of product and process design

2 1 Product and Process Design

cascade down into all the activities that follow. This leads to significant costsavings in manufacture and increases the product’s reliability as there is less to gowrong. To assist parts rationalisation various concepts have been developed andthey form the basis of design for manufacture and assembly guidelines [3]. Theseconcepts have been applied in industry to streamline design but the increasingfunctionality and the sophistication of products is taking us toward more and moreparts and this requires new approaches for parts rationalisation, such as those basedon costing [1]. The methodology outlined in this monograph focusses on this.

1.2.2 Part Planning

Part planning has been the domain of those well versed in manufacturing engi-neering. It is a skill-based activity and the specialists often arose from the factoryfloor and brought with them considerable heuristic knowledge of processes andequipment involved, such as jigs, fixtures and machine tools. The author wentthrough this process and gained a great deal of knowledge about part manufac-turing activity. The details in part planning are of technical nature and theycommence with the material and the volume involved. These variables influencethe manufacturing process and tooling and generate the macro-aspects of partplanning. In these macro-aspects are inherent the micro-tasks that help to createthe part form. These are the shaping processes, such as milling and turning, andthey constitute the micro-aspects of process planning. The macro-layer can begenerated as a sequence of tasks and these tasks then analysed for their micro-requirements as shown in Fig. 1.2.

The variables influencing the manufacturing cost are materials, equipmentand the tasks involved that create the part form. Cost is locked in as soon asthe part form is finalised and every aspect of it after that influences the costof manufacture, particularly the surfaces to be generated and the tolerances tobe met. Once the manufacture starts the cost starts to build up from theamount of material involved including the scrap amount. To process thematerial special equipment is often required and this brings in their cost ofutilisation as shown in Fig. 1.3. Manufacturing expertise is applied throughthe analysis of tasks and this involves the setting up of the process. Thisgenerates the total time required for the process including allowance forinefficiency, which is always present. The costing of time is another matterand it varies considerably depending on the location of manufacture, espe-cially the country of manufacture. In the recent times this is evident fromthe relocation of manufacture to China and India. The time involved in themanufacture of a product is same everywhere but the cost is not, hence theongoing effort to reduce it by shifting location around the world and thistrend will continue in the foreseeable future.

1.2 Product and Process Design 3

1.2.3 Assembly Planning

Assembly planning is no different from that of part planning, the taskanalysis is once again the key requirement. Assembly process has a sequenceof macro-tasks and their analysis leads us to the equipment and timerequirements as illustrated in Fig. 1.4. The macro-sequence of tasks helps usto establish the overall assembly process and this starts with the first com-ponent involved and finishes with the final task. This task-based common-ality provides the underlying unity to part planning and assembly planning,this can be utilised to capture the overall manufacturing information contentof a product. This is a holistic approach to product design because it isbased on total cost rather than number of parts. The use of standard partsinstead of a single unified part can sometimes reduce the cost of manufactureand this requires an overall perspective of manufacturing. In assembly thecost of parts is brought in by the Bill of Materials (BOM), after that the costmodel does not differ much from that for part manufacture as illustrated inFig. 1.5. The final cost in this case reflects the total cost of manufacturingthe product, including assembly. What follows after part planning andassembly planning is the design of a physical system to produce the productin volume. For this the process designs for part manufacture and assemblybecome the inputs.

Create workelements

Manufacturing sequence

Workelement analysis

Process Plan Time and Cost

Fig. 1.2 Part planning

4 1 Product and Process Design

1.3 Manufacturing System Design

Whether the product is manufactured in volume or as a one off the task analyses ofpart manufacture and assembly require a physical system to produce it. For this thetask models become the input for the manufacturing system design as illustrated inFig. 1.6.

1.3.1 Workstations

Volume manufacture requires concurrency of tasks and in physical systems this isprovided by the workstations. The number of workstations is determined by thevolume to be produced, shift time and the total time of overall tasks. This leads tothe cycle time per station.

Often it is impossible to aggregate the task times involved to be exactly thesame as the cycle time, some stations therefore end up being less than fully

Material cost including scrap amount

Capital cost and amortisation of equipment

Setup time, process time and efficiency

Rates of direct labour and overheads

Accumulative cost of all workelements

Output Cost of part manufacture

Fig. 1.3 The costing of part manufacture

1.3 Manufacturing System Design 5

Part cost through BOM

Capital cost and amortisation of equipment

Setup time, process time and efficiency

Rates of direct labour and overheads

Accumulative cost of all workelements

Output Cost of product manufacture

Fig. 1.5 The costing of assembly process

Create workelements

Assembly sequence

Workelement analysis

Process Plan Time and Cost

Fig. 1.4 Assembly planning

6 1 Product and Process Design

occupied and this leads to inefficiencies. The cycle time reflects the throughputrate or how many will be made per hour or per day, as for example in a bakery orin a car plant. If the production requirement is very high then the cycle time can besignificantly less than the smallest task time. This leads to problems which areovercome by parallel workstations performing the same task. This helps to reduce

Throughput

Optimisation

Layout

Optimisation

Workstations

Optimisation

Assembly

Optimisation

Part

Optimisation

Product

Optimisation

Product Attributes Lifecycle Issues Number of Parts

No

Yes

Acceptable

Throughput Strategy

No

Yes

Acceptable

Part Attributes Task Sequence

Tooling

Assembly Attributes Task Sequence

Time

Workstations

Layout Planning

Manufacturing System

Production

Time and Cost

Assembly Planning

Part Planning

Product Planning

Manufacturing Time Product Volume

Line Balance

Process Equipment Transfer Systems

Layout Design

Just in Time Kanban

Buffer Levels

Product

Fig. 1.6 Manufacturing system design

1.3 Manufacturing System Design 7

the task time by producing more in the same time through concurrent activity. Thisapplication of parallel tasking at micro-levels helps to solve manufacturabilityproblems to meet high production rates. If the task time is in seconds then adedicated automation is often the only answer. In more complex products manu-facture in high volumes the financial and the human resource issues become muchmore critical and generally involve high levels of business risk.

1.3.2 Layout Planning

Workstations require layout arrangements in order to meet the demands ofequipment and transfer systems. In high volume manufacture layout becomes asignificant part of the overall system design and transfer lines are examples of this.They involve machining cells and automated movement of parts and subassem-blies, effectively the overall task models of parts manufacture and assembly aremechanised. One important point to note here is that in such settings the dynamicaspects of process design also become very significant. The static picture ofmacro-tasks and their micro-analysis does not bring to surface the dynamicsinvolved or the mass and motion effects of parts and assemblies. A transfer line infull motion is a highly dynamic system, it is a process design in motion. Thisbrings into play many other aspects of mechanical design and control systemswhich are beyond the scope of this monograph. One important advance in recenttimes has been the robotics technology. It has opened up new possibilities throughfixed platforms and autonomous systems. Although it is an advancement ofnumerical control systems, the dexterous capabilities of robotics allow automatedtransfers and this enables the layout to be considered in a new light. There was aweakness in the processing systems for parts manufacture and assembly centeringon the handling systems and this has been addressed by the robotic technology.

1.3.3 Throughput Strategy

The need for continuous flow of production resulted in just-in-time type ofmanufacturing, which in turn lead to large supply chain systems involving severalcountries. Such large systems are sensitive to unforeseeable circumstances that candelay the delivery of parts and assemblies. To overcome this buffer levels werecreated and there was a time when such buffer levels used to be very significant,until it was realised that this involved tying up large capital that could be moreeffectively used. This led to lean manufacturing which is an extension of just-in-time manufacturing in order to reduce the buffer levels to minimum or to eliminatethem completely. The manufacturing company that took the lead to introduce thiswas Toyota of Japan, hence the just-in-time type of manufacturing is often calledthe Toyota System. Now even non-volume manufacturers, such as aircraft

8 1 Product and Process Design

manufacturers, are applying such concepts to improve the productivity of theirworking capital.

In summary, process design translates product design into manufacturingrequirement and this leads to time and cost of manufacture. It is about establishingthe macro-tasks involved and to determine their micro-requirements. There is anunderlying unity to part planning and assembly planning and this centres on theneed for task analysis in both cases. This unity can be leveraged for integratedmanufacturing process design and costing. In the following chapters we look atthis in detail.

References

1. Otto, K., & Wood, K. (2001). Product design—techniques in reverse engineering and newproduct development. NJ: Prentice Hall.

2. Prabhakar Murthy, D. N., & Blischke, W. R. (2005). Warranty management and productmanufacture. Springer, UK.

3. Boothroyd, G., Dewhurst, P., & Knight, W. (1994). Product design for manufacture andassembly. Marcel Dekker, New York.

1.3 Manufacturing System Design 9