IENG 451 JIT

Production Physics Little’s Law Throughput = WIP/Cycle time For fixed capacity, cycle time and WIP or proportional – thus you can increase throughput either by increasing WIP or by decreasing cycle time

Production Physics Law of variability – increasing variability inevitably degrades the performance of the system Law of variability buffering – variability in a production system will be buffered by some combination of inventory, capacity, or time

JIT Principles Don’t produce something unless a customer has ordered it Level demand so that work may proceed smoothly throughout the plant Link all processes to customer demands through visual tools (kanbans) Maximize the flexibility of people and machinery

Pull Systems Nobody upstream produces a good or a service until somebody downstream asks for it

Pull Systems Nobody upstream produces a good or a service until somebody downstream asks for it

Pull Systems Nobody upstream produces a good or a service until somebody downstream asks for it

Kanban Rules Never ship defective items Customer withdraws only what is needed Produce only quantity withdrawn by the customer Level production Use kanban to fine-tune production Stabilize and strengthen the process

Production orders Batch of 10 vs Batch of 100 – Adjust more quickly to demand – Better sense of takt time – Fewer peaks and valleys – Better control of abnormality production

Pull Systems Type A – Frequent orders with short lead times, most common, replenishing gaps created in the finished goods storage Type B – Infrequent orders or long lead times, pacemaker is usually midstream Type C – Combination of type A and type B running in parallel

Process Flow Tools Process Mapping SIPOC – S upplier, I nputs, P rocess, O utputs, C ustomers Spaghetti diagrams Swim Lane flow charts Value Stream Mapping

SIPOC Charts

Value Stream Mapping VSM helps grasp current condition and identify improvement opportunities Improvement events create localized improvements; VSM provides a vision and plans that connect all improvement activities VSM allows you to see waste and plan to eliminate it

What is VSM Planning tool to optimize results of reducing waste

Five Principles for VSM Specify value from end customer standpoint Identify value stream for each product family Make the product flow Customer pulls the system Manage towards perfection

Value to Customer ? How does current product / process disappoint customers value expectation: – Price ? – Quality ? – Delivery ?

What Flows Manufacturing; materials are the items that flow Design & development; designs flow Service; customer needs are the items Administration; internal customer needs are the items

Current State (Manuf.)

Future State – (Manuf.)

VSM Steps Determine the individual product or service you will map Draw the process flow

VSM Steps Add material flow

VSM Steps Add Information flow

VSM Steps Collect process data and connect it to boxes on chart Add process and lead times