Space Requirements. Space Requirements

Transcription

1 Facility Location, Layout, and 96 Production Rate Determination Market forecast is translated into production quantities» Desired output = O n = (1+Safety Factor)*Forecast» For k = n,...,1 Ok Ik = 1 P k» where I k = Production input to operation k O k = Production output from operation k P k = Scrap rate for operation k» Example Three operations, scrap rates 3%, 2%, and 4% Forecast = 180,000 units per year (plus 10% allowance) Input quantities are 217.0, 210.5, and units per hour to achieve output of 198 per hour 100 Equipment Requirements Number of machines required for the desired production rate at each processing stage» P ij = desired production rate for product i on machine j» T ij = production time for product i on machine j» H ij = number of hours available for production, including an allowance for machine downtime, etc.» M j = number of machines of type j required» n = number of products Then, M j = n PT ij ij H i = 1 ij Could also use probability distributions instead of point estimates Industrial Engineering 1

2 Facility Location, Layout, and 101 Employee Requirements For manual assembly operations, we can use the same method as machine requirements n PT ij ij Aj = H i= 1 ij In some cases, an operator may tend multiple machines» Assume all times are deterministic Use multiple activity chart or human-machine chart Especially useful for tending non-identical machines For identical machines, use a prescriptive method that minimizes the total cost. Tradeoff is between operator idle time and machine idle time.» Assume all times are probabilistic Use queueing theory or simulation Might use a pool of operators to serve a group of machines 102 Space Determination -- Must consider» Raw material, In-process inventory, and Finishedgoods storage» Aisles, cross aisles, and main aisles» Receiving and shipping» Material handling equipment storage» Tool rooms and tool cribs» Maintenance» Packaging» Supervision» Quality control and inspection» Health and medical facilities» Food service» Lavatories, washrooms, etc.» Offices» Employee and visitor parking» Receiving and shipping parking» Other storage Industrial Engineering 2

3 Facility Location, Layout, and 103 Production-center method (Workstation specification)» Factor determined for a single machine and all the equipment and space required for its operation. This is multiplied by the number of pieces of equipment and summed over all equipment types Converting method» Estimate the space requirements from those required for the present layout (or a similar one in another facility) Roughed-out layout method» Templates or models are used to estimate space Space-standards method» Use standards based on past successful applications Ratio trend and projection method» Used for general space requirements. Establishes a ratio of square feet to some other factor, such as direct labor hour, units produced, etc. 104 Workstation specification Space for equipment, materials, and personnel Equipment space includes space for» Equipment» Machine travel» Machine maintenance» Plant services Materials areas include space for» Receiving and storing materials» In-process materials» Storing and shipping materials» Storing and shipping waste and scrap» Tools, fixtures, jigs, dies, and maintenance materials Industrial Engineering 3

4 Facility Location, Layout, and 105 Workstation specification (cont.) Personnel area includes space for» Operator Obtained directly from method of performing the operation determined by a motion and ergonomic study» Material handling Obtained directly from method of performing the operation determined by a motion and ergonomic study» Operator ingress and egress Minimum of 30 aisle for operator travel past stationary objects Minimum of 36 aisle for travel between a stationary object and an operating machine Minimum of 42 aisle for travel between two operating machines Simulate the operator performing a typical days work to ensure the adequacy of the space allocation and the efficiency of the operation. 106 Department specification May not be the sum of the individual workstations Some machine maintenance, plant services, incoming and outgoing materials, and operator ingress and egress areas may be combined Additional space is required for material handling within the department Aisle space requirements can not be determined exactly but the following table can serve as a guide Aisle allowance If the largest load is percentage is Less than 6 ft Between 6 and 12 ft Between 12 and 18 ft Greater than 18 ft Industrial Engineering 4

5 Facility Location, Layout, and 107 Aisle Arrangement Located to promote efficient flow» Aisles too narrow may result in congested facilities, high levels of damage, and safety problems» Aisles too wide may result in wasted space and poor housekeeping practices Widths determined by considering the type and volume of flow (see Table 4.4 for widths in primarily one-way aisles) Curves, jogs, and nonright angle intersections should be avoided Aisles should be straight and lead to doors Aisles along the outside wall should only be used for entering and leaving the facility Column spacing should be considered Industrial Engineering 5