Chapter 5 Lean Manufacturing System Concept 1t5c8

LEAN PRODUCTION SYSTEM CONCEPT

Disusun Oleh; Candra Setia Bakti, ST., MT

LEAN THINKING Key Principles of Lean Thinking  VALUE - what customers are willing to pay for  VALUE STREAM - the steps that deliver value  FLOW - organizing the Value Stream to be continuous  PULL - responding to downstream customer demand  PERFECTION - relentless continuous improvement (culture) --- Lean Thinking, Womack and Jones, 1996

Defining Lean

Lean is: “A systematic approach to identifying and eliminating waste (non-value added activities) through continuous improvement by flowing the product at the pull of the customer in pursuit of perfection.”

Lean Goals- TPS  Zero

defects  100% value-add  Lot size of one  Pull of the customer

GOAL

Lean Production System Goals - highest quality, lowest cost, shortest lead times Just-In-Time

Involvement

•continuous flow •takt time/pace •pull system •triggers

Heijunka

Standardized Work

Jidoka •separate man & machine work •identify abnormal conditions •poka yoke

Kaizen

Stable Manufacturing Process

Lean = Eliminating the waste Value added

8 Wastes 5%

   

Non-value added

   

Overproduction Excess inventory Defects Non-value added processing Waiting Underutilized people Excess motion Transportation

Typically 95% of Total Lead Time is Non-Value Added!!!

Value Added/Non-value Added 

Value-added:

 ANY ACTIVITY THAT PHYSICALLY CHANGES THE

MATERIAL BEING WORKED ON (not rework/repair!)





Machining

Knitting



Drilling

Spreading/Cutting



Assembly

Dying



Painting

Sewing

Non-value added:

 ANY ACTIVITY THAT TAKES TIME, MATERIAL, OR

SPACE BUT DOES NOT PHYSICALLY CHANGE THE MATERIAL



Sorting

Stacking



Counting

Checking

Just-in-Time

Pull System

•Pull System is a flexible and simple method of controlling/balancing the flow of resources. – Eliminating waste of handling, storage, expediting, obsolescence, repair, rework, facilities, equipment, excess inventory (work-in-process and finished).

•Pull System consists of: – Production based on actual consumption – Small Lots – Low inventories – Management by Sight – Better Communication

Traditionally... one control operation takes the customers’ orders, creates, and sends out schedules to all processes. Production Control

Weekly Schedule

Cutting Transfer

Press Washer

Assembly Assembly

Shipping

Push System Material Movement 

In traditional manufacturing, all process departments receive schedules and produce to it.



Each process produces their parts and forwards them to the next process.



This is commonly referred to as the Push System.

What happens……? 

A problem may occur when a change is made either because the order changes, the equipment goes down, or material is not available .

Production Control Weekly Schedule

I I Transfer Cutting

Washer press

I

Assembly Assembly

I

I

Shipping

I

Pull System Material Flow 

Lean – flow through the factory with minimum interruption

Painting I

1Shift

Cutting 1Shift 33

Press

FIFO

1Shift 204

Assembly

FIFO

C/T= 9sec 1Shift

Flow where you can, Pull where you can’t

I

Schedule is provided to final production department

Example of a Pull System

Schedule

Each process upstream maintains standard stock levels.

Process

A

Process

B

Customer

Process

C

Process

D

Schedule

The final production department withdraws needed materials from its supplier operation

Process

A

Process

B

Customer

Process

C

Pull

Process

D

Schedule

The supplying department now produces to fill up its stock level. It withdraws the supplies it needs from the upstream process.

Process

A

Process

B

Pull

Process

C

The units are produced and shipped to the customer.

Customer

Process

D

Schedule

The customer’s needs are filled long before the initial department even knows about the request.

Process

A

Pull

Process

B

Customer

Process

C

Process

D

Just-in-Time Pull System • Kanban - A signal to indicate when more parts are needed (Order or Produce) - Card, empty Bin, In Process Kanban (IPK) on plant floor

Types of Kanban



Main types: 



Withdrawal Kanban 

Inter-process withdrawal



Supplier

Production Instruction Kanban 

In-process Kanban



Signal Kanban (for lot production with longer set-up time)

Between two processes (Internal to Plant) Between customer and supplier

Internal to process

Withdrawal Kanban Card



The information on a withdrawal Kanban includes: 

Item name and part number



FROM-preceding process and storage location



TO- subsequent or consuming process and delivery location



Standard quantity and container type



Item code (abbreviation of part number-optional)



Parent product (name of final assembly-optional)

Just-in-Time Pull System

Standard Production or “Move” Kanban

Just-in-Time Quick Changeover (Set-up Reduction) Single Minute Exchange of Dies (SMED) •a series of techniques for changeovers of production machinery in less than ten minutes (single digit minutes) Set-up Reduction Program Goals •To achieve smaller lots •To maintain consistent quality •To minimize inventory •To reduce lead times •To address frustration of setup personnel

Just-in-Time Basic SMED Principles  Identify

internal vs. external

changeover tasks  Analyze

each task’s real

purpose and function  Focus

on no/low cost

solutions  Aim

to eliminate

changeover time

Just-in-Time No/Low Cost Solution: One-Turn Methods Pear-Shaped Hole Method

Tighten Here Attach and Remove Here

Just-in-Time Takt Time = Demand Rate Takt Time =

Work Time Available Number of Units Sold

GOAL: Produce to Demand

Developing a Lean Factory Summary - Just-in-Time •Pull Systems/Kanban •Point Of Use Storage •Quick Changeover/Setup Reduction •Continuous Flow •Takt Time