Process Selection and Facility Layout

Process selection – Deciding on the way production of goods or services will be organized Major implications – Capacity planning – Layout of facilities – Equipment – Design of work systems Introduction

Forecasting Product and Service Design Technological Change Capacity Planning Process Selection Facilities and Equipment Layout Work Design Process Selection and System Design Inputs Outputs

Key aspects of process strategy – Capital intensive – equipment/labor – Process flexibility – Adjust to changes – Design – Volume – Technology Process Strategy

Variety – How much Flexibility – What degree Volume – Expected output Job Shop Batch Repetitive Continuous Process Selection

Process types

Job shop – Small scale, wide variety of goods Batch – Moderate volume, flexible Repetitive or assembly line – High volumes of standardized goods or services Continuous – Very high volumes of non-discrete goods Projects – Non-routine work, unique set ob objectives, limited timeframe and resources Process types and volume

Product – Process Matrix The diagonal of the matrix represents the ideal choice of processing system for a given set of circumstances.

Functions/activities affected by process choice Job variety, process flexibility, unit cost Volume Limited (not ongoing)

Some examples (find the process type of each) Movie production Bakery Restaurant (non fast food) University Car repairing (car mechanic shop) Oil mining Producing office tools Veterinarian Project Batch Job shop Continuous Repetitive Job shop

Product and service life cycles Alongside the life cycle the sales and with it the production volume can change. Thus managers must be aware of the change in the optimal processing system. (the necessity of change is highly dependent on the particular good or service)

Example Computer building shop in a garage (working for order only, one computer at a time for given purposes) The shop hires some workers and producing some dozens of computers for one customer at a time Computer factory is established, creating large number of computer series The R&D function of the firm invents a new computer prototype Job shop Batch Repetitive Project

Product/Service Profiling Linking key product or service requirements to process capabilities. Design the process with taking into consideration the following: – Range of products/services – Expected order size – Pricing – Expected frequency of changes in schedules etc. – Order-winning requirements – …

Sustainable production Non-polluting Conserving natural resources & energy Economically efficient Safe and healthful for workers, communities and consumers Socially and creaqtively rewarding for workers

Automation: Machinery that has sensing and control devices that enables it to operate – Fixed automation – Programmable automation Automation of production and services

Advantages of automation Low variability in performance and quality Machines do not – get bored or distracted – go out on strike or ask for higher wages – lower variable costs

Disadvantages Higher initial (investment) cost and Higher fixed costs Lower felxibility Higher skills needed Lower morale of human workforce Need for standardisation – Products – Processes – Equipment and materials etc.

Computer-aided design and manufacturing systems (CAD/CAM) Numerically controlled (NC) machines Computerized numerical control (CNC) Direct numerical control (DNC) Robot: mechanical arm + power supply + controller Manufacturing cell Flexible manufacturing systems (FMS) Computer-integrated manufacturing (CIM) Automation

Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system Facilities Layout

Requires substantial investments of money and effort Involves long-term commitments Has significant impact on cost and efficiency of short-term operations Importance of Layout Decisions

The Need for Layout Decisions Inefficient operations High (variable) cost Bottlenecks Changes in the design of products or services The introduction of new products or services Safety Changes in environmental or other legal requirements Changes in volume of output or mix of products Changes in methods and equipment Morale problems

Objectives of facility layout Main: smooth flow of work, material and information Supporting objectives:

Product layouts Process layouts Fixed-Position layout Combination layouts: – Cellular layout (& group technology) – Flexible manufacturing systems Basic Layout Types

Product layout – Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow Process layout – Layout that can handle varied processing requirements Fixed Position layout – Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed Basic Layout Types

Used for Repetitive or Continuous Processing Product Layout

High rate of output Low unit cost Labor specialization Low material handling cost High utilization of labor and equipment Established routing and scheduling Routing accounting and purchasing Advantages of Product Layout

Creates dull, repetitive jobs Poorly skilled workers may not maintain equipment or quality of output Fairly inflexible to changes in volume Highly susceptible to shutdowns Needs preventive maintenance Individual incentive plans are impractical Disadvantages of Product Layout

A U-Shaped Production Line

Advantages/disadvantages of U-shaped lines Shorter distances for workers & machines Permits communication thus facilitates teamwork More flexible work assignments Optimal if the facility has the same entry and exit point If lines are highly automated, there is no need for communication and travel If entry points are on the opposite side as exit points Noise and contamination factors are increased in the U-shape

Dept. A Dept. BDept. D Dept. C Dept. F Dept. E Used for Intermittent processing Job Shop or Batch Process Layout (functional) Process Layout

Can handle a variety of processing requirements Not particularly vulnerable to equipment failures Equipment used is less costly Possible to use individual incentive plans Advantages of Process Layouts

In-process inventory costs can be high Challenging routing and scheduling Equipment utilization rates are low Material handling slow and inefficient Complexities often reduce span of supervision Special attention for each product or customer Accounting and purchasing are more involved Disadvantages of Process Layouts

Fixed-position layouts The product or project remains stationary and workers, materials, and equipment are moved as needed. If weight, size, bulk, or some other factor makes it undesirable or extremely difficult to move the product. E.g. firefighting, road-building, home-building, drilling for oil etc.

Cellular Production – Layout in which machines are grouped into a cell that can process items that have similar processing requirements Group Technology – The grouping into part families of items with similar design or manufacturing characteristics – Makes cellular production much more effective Cellular Layouts

Traditional process layout Cellular layout

DimensionFunctionalCellular Number of moves between departments manyfew Travel distanceslongershorter Travel pathsvariablefixed Job waiting timesgreatershorter Throughput timehigherlower Amount of work in process higherlower Supervision difficultyhigherlower Scheduling complexityhigherlower Equipment utilizationlowerhigher Functional vs. Cellular Layouts

Flexible manufacturing systems FMS: a group of machnies designed to handle intermittent processing requirements and produce a variety of similar products. CIM (Computer Integrated Manufacturing): a system of linking a broad range of manufacturing activities through an integrating computer system

Warehouse and storage layouts – Minimizing movement & picking time and cost Retail layouts – Presence & influence of customers Office layouts: – Information is computerized, image of openness Service Layouts

Design Product Layouts: Line Balancing Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements. This way the idle time will be minimized, utilization will be maximized. Specialization: dividing work into elemental tasks that can be performed quickly and routinely.

Cycle Time Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit. t max < Cycle time < ∑t

Determine the Minimum Number of Workstations Required Theoretical N min is not necessarily will be the N actual. The latter is affected by other technical and practical considerations, too. N min ≤ N actual (rounded up to the next integer)

A diagram that shows elemental tasks and their precedence requirements. A simplified precedence diagram a b cd e 0.1 min. 0.7 min. 1.0 min. 0.5 min.0.2 min. Precedence Diagram

Assume that the desired output is 480 units per day. The facility is working 8 hours a day. The elemental tasks and their connections are shown on the previous slide. Calculate the cycle time. Calculate the minimum number of workstations. Arrange the tasks to these workstations in the order of the greatest number of following tasks. Example 1: Assembly Line Balancing

Workstation Time RemainingEligible Assign Task Revised Time Remaining Station Idle Time a, c * c ** none*** ac-ac bb de-de- de-de Total: 0.5 Example 1 Solution * Tasks that have no predecessors. ** b is not eligible, because it needs more time than than the remaining. *** Every available task needs more time than 0.2.

Efficiency %= 100 x (1 – Percentage of idle time) Calculate Percent Idle Time and efficiency

Line balancing procedure

Assign tasks in order of most following tasks. – Count the number of tasks that follow Assign tasks in order of task time. Assign tasks in order of greatest positional weight. – Positional weight is the sum of each task’s time plus the times of all following tasks. Line Balancing Heuristics

Example 2 Working day is 8 hours and the desired output rate is 400 units per day. Draw the precedence diagram. Compute the cycle time & the minimum theoretical number of workstations required. Assign tasks to workstations according to the greatest number of following tasks. Tiebreaker: longest processing time goes first. Calculate Percent idle time & efficiency.

Solution 2 CT = (8*60)/400= 1.2; N min = ∑t i / CT = 3.17 → 4 abe cfdhg Work stationTasks assignedIdle time WS1a,c,b0 WS2d,e0.3 WS3f0.2 WS4g,h0.5 Percentage idle time = 1.0 / (4*1.2) = 20.83% Efficiency = 100 – = 79.17%

Other approaches Paralell workstations Cross-train workers (dynamic line balancing) Mixed model line (more product on the same line)

1 min.2 min.1 min. 30/hr. 1 min. 1 min. on average 1 min. 60/hr. 30/hr. 60/hr. 30/hr. Bottleneck Parallel Workstations 2 min.

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