Planning in production systems MRP systems, MRP II, JIT Slovak University of Technology Faculty of Material Science and Technology in Trnava

Material Requirements Planning (MRP) MRP is a software based production planning and inventory control system used to manage manufacturing processes. MRP is a calculation method geared toward determining how much of which raw materials are required and roughly when they should be ordered to fulfill a set of product orders.

An MRP system is intended to simultaneously meet three objectives: Ensure materials and products are available for production and delivery to customers. Maintain the lowest possible level of inventory. Plan manufacturing activities, delivery schedules and purchasing activities.

MRP generally consists of four steps: Bill of Materials Explosion - looking backward from each product, determine which intermediates and raw materials are required, and in what quantities. Netting - compare the above quantities against current inventory. Lot Sizing - determine how the needed materials will be purchased or produced. Start Date Determination - based on cycle time information, determine when each order should start production.

MRP system structure

Level of stock

Manufacturing Resource Planning Manufacturing Resource Planning (MRP II) orientation to production sources planning all information current, planning function and production control integrate to one logical chain cross material current, using continuous planning principles - production process hierarchy support.

Automated production

JIT (Just in Time) base idea – to optimized buffering stocks, which help us to control supplies level; high supplies level = small effectiveness, more then supplies control – philosophy based on continual deficit finding out and elimination on all organizations levels.

JIT can see as: philosophy or full access to production technics which are used for production system design and operation beam house control system - kanban = dispatch note.

Objective of JIT Produce only the products the customer wants. Produce products only at the rate that the customer wants them. Produce with perfect quality Produce with minimum lead time. Produce products with only those features the customer wants.

JIT Principles Create flow production  one piece flow  machines in order of processes  small and inexpensive equipment  U cell layout, counter clockwise  multi-process handling workers  easy moving/standing operations  standard operations defined Establish “TAKT” time  rate at which the customer buys a product Build Pull Product  use of kanban system

By decreasing supplies level we can see hidden problems with two sources: extern – mistakes in delivery - customers relations intern – mistakes which reach as consequence of quality deficient (material, production engineering, production process organization, work power, goods and technical documentation design)

Solutions extern problems source - build reliable stable delivers chain and reliable customers intern problems source - complex quality increasing and monitoring – TQM (Total Quality Management), active production process quality assurance – SPC (Statistical process control); it try to do ZD (zero defects).

Aim of JIT 1. Dodge to generality 2. Avoid the loss 3. Continuing improvement

1. Dodge to generality by the customers – fast change of claim and preferences – although we need to retain adequate costs, offer palette of goods and short delivery dead-lines by the delivers – first step in production; important in storage nonexistence to achieve quality and right supplies or blank in right time

by the workers  absence and another problems can be reduced with right workers motivation, increasing the work claim, work organization, higher work motley and easy identification their portion to making good  workers education - achieve decreasing level of goods mistakes  preference before making simply monotone operations continuously by many workers have to be making complex operations by one workers by claim of trade – is not anytime constant

2. Avoid the loss Overproduction Idle time and production storages Transporting Mistakes

3. Continuing improvement effective increasing, looses elimination, indemnity for reliability, making production discipline etc. (unending process) KAIZEN philosophy - sense to have trying achieve production without mistakes for all goods, because mistakes destroying continuous production current (continuously increasing process).

JIT Advantages Shortened lead time Reduced time spent on non-process work Reduced inventory Better balance between different processes Problem clarification

Limitations of JIT Preconditions to JIT  trust must be present labor/management suppliers/consumers  recognition of processes  familiarity with problem solving  quality at the source  agreement over value and waste

Limitations of JIT Right Settings  applicable in growth to maturity phases of Product Life Cycle  standard product Steinway and JIT  standard/fixed pay-rate problems with piece-rate scheme Universal agreement that change needed