EMS ‘Lean Sigma’ shortens cycle time, reduces costs & improves quality
what is being used and what needs replen- was reduced from 2.8 days to 1.1 days. The for each process, an electrical common
ishing. Inventory is reduced because you secondary benefits are the reduction of part checking system set-up, centralizing
pull just what is needed, when it’s needed, WIP and control over calculated buffers, management of the feeder and material,
speeding response time in planning and meaning that at no point in time will the and instituting a new material replenish
reducing the wait for materials. Materials calculated maximum of WIP be exceeded. set-up process.
are delivered directly into the manufactur- These benefits are rendered based on a By revising the layout of the produc-
ing process so some of the component defect free, balanced single-piece pull flow tion line to a work cell and material flow
buffer can be removed and manufacturing with kanban replenishment systems. approach, line capacity increased 42%,
is done to production instead of stock, The EMS’s plant in Mexico, previously from 1.3 to 1.8 pieces per square meter.
resulting in just-in-time delivery with single took about 20 weeks to source and pur- Line capacity per direct work (human
piece flow. On demand material acquisi- chase materials and have them delivered, resources) increased 40%, from 2.7 to
tion minimizes obsolescence and helps to about a week to set up the SMT lines and 3.7 pieces per person. This was the result
ensure that purchased materials meet the do the SMT assembly, and one or two of rebalancing the assembly process for
most up-to-date environmental compliance days for final assembly and test and to get manufacturing time and through resource
requirements. The cost of capital is re- products packaged and ready to ship. Now, reduction. An example of a layout change
duced. Things happen simultaneously. An with the demand pull system, sourcing and can be seen in Figure 1.
MRP system is used for inventory planning receiving time remain the same at about 20 As in the Mexico plant, the operation
and to get materials from the warehouse to weeks, but SMT production takes only one depends on real consumption rather than
the assembly line quickly and as needed. to two days because only product that is forecasted consumption, which minimizes
To improve response time and control needed is manufactured, so there is a limit the buffer level for warehouse space and
work in process (WIP), the maximum to the amount of work in progress. supplier response time reduction. Demand
inventory for WIP is designed between The China, plant achieved similar response time went from 14-21 days to
the SMT and final assembly steps based improvement. Changeover time for the 10-12 days. Expectations are that will be
on a process map. A factory throughput handling process improved 55%, from shortened to eight to nine days by reducing
time (FTT) project provides well-controlled 40 minutes to 18 minutes. This was due supplier response time to reduce surface
WIP. Results show that work in progress to having standard operating equipment mount component hub buffer levels to one
to two days for stored space savings.
Previous layout of assembly floor conclusion
Lean Sigma consists of pull processing,
perfect first-time quality, waste minimiza-
tion, continuous improvement, flexibility,
Assembly Assembly Assembly Assembly Assembly
building and maintaining a long-term
relationship with suppliers, automation,
load leveling and production flow, and
Material in
visual control. Using the pull principal en-
ables the EMS to produce almost anything
Assembly Assembly Assembly Assembly Assembly
with short lead times and deliver when the
Material
customer wants it almost all the time. Lean
flow thinking is part of the company culture,
which can create profitable business only
Tuning Tuning Tuning Tuning Tuning
when every supplier in the partnership
helps translate its principle in an effective
way. Using an outsourcing partner with a
global footprint and the ability to provide
Current layout of assembly floor
rapid response to changes in capacity and
services allows OEMs to optimize their
Material in
total cost of ownership without incurring
restructuring costs.
Assembly Assembly Assembly
Assembly Assembly Assembly
Assembly Assembly Assembly
Assembly Assembly
Material flow
Tuning Tuning Tuning Tuning
Figure 1. Changing to a work cell and material flow approach increased line capacity 42%.
12 – Global SMT & Packaging – May 2009 www.globalsmt.net
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