Efficient line changeover: the key to lean manufacturing
!
Figure 4. Solder paste deposition.
Figure 5. Process improvement effect on operating efficiency.
Cost savings Temp: 23 deg ment (ROI) of less than nine months.
The cost savings of the reduced setup and Humidity: 40%
changeover time was calculated in terms of conclusion
direct labor savings using a full absorption Paste data including paste height, volume With the aforementioned productivity
hourly rate. The direct labor savings was: and area was collected over a thirty-board challenges in mind, many companies
sample. Definition of print was of a consis- have programs in place to improve their
Baseline Process: tently high quality throughout the entire equipment utilization. Initiatives such as
15 minutes, 22 seconds x 500 two-sided sampling with solder paste height closely Six Sigma, lean manufacturing and SMED
kits x 3 machines per line x 10 lines = following the predicted average paste are being implemented. As shown in the
3,840 hours annual height of 112 microns as shown in Figure 4. case study, a simple area such as board
3,840 X $30.00 full absorption cost per It is widely known that the maximum support changeover can yield a substantial
hour improvement in operating efficiency can operational savings.
be obtained by eliminating defects during a As in this case study, the goal and ob-
Improved Process: manufacturing operation, since they repre- jective to reduce line setup and changeover
2 minutes, 8 seconds x 500 two-sided kits x sent non-valued-added cost.
3
Additionally, time to less ten minutes is achievable. En-
3 machines per line x 10 lines = 533 hours a corresponding reduction in non-produc- tire factory retooling to utilize the benefits
annual tive equipment changeover time results of this new generation of substrate support
533 X $30.00 full absorption cost per hour in a significantly greater improvement in system is essential to maintain a com-
operating efficiency than faster cycle time petitive position in the global electronic
Cost of changeover using old method: as shown in Figure 5. manufacturing market.
$115,200 per year In addition to the direct labor savings
Target changeover time: 7.5 minutes = 50% resulting from implementing the substrate references:
improvement support systems, a substantial savings was 1. Lasky, Ron Ph. D., “Real Time Costing
Actual changeover time: 2 minutes, 8 obtained in terms of improved operational as a Tool to Improve Profitability,”
seconds = 87% improvement efficiency. Reducing board support setup APEX 2000 Proceedings of the Techni-
Cost of changeover using new method: and changeover time improved equip- cal Conference, March 2000, Session
$15,990 per year ment utilization by 9.6%, resulting in an P-SM2, pp. 1-3.
Annual cost savings: $99,210 18% improvement in overall operating 2. DEK International, Global Applied
efficiency. Process Engineering, Internal Docu-
Process control Benefits derived from implementing ment.
To insure that the process reliability of the the substrate support systems for the case 3. Lasky, Ron Ph. D., “Critical Issues in
screen printing operation was not compro- study operation include: Electronics,” Nepcon West 98 Confer-
mised with the new support system, solder 1. Consistent solder paste deposi- ence Proceedings, March 1998, pp.
paste deposition was monitored, with tion within height, volume and 183-197.
visual inspection concentrating on print area quality requirements.
quality and bridging.
2
2. A significant reduction in setup Douglas Farlow is president & CEO of Cali-
and changeover time for the ef- fornia-based Production Solutions. He can be
Substrate thickness: 1.6 mm fected production equipment. reached at
dfarlow@production-solutions.com.
Applicator: 250mm squeegees 60 degrees 3. A marked improvement in
Print Speed: 35 mm/s equipment utilization.
Separation speed: 10mm
Based upon this study, it was determined
System Pressure: 5.6 Kg
that implementing substrate support sys-
Print Gap: On contact
tems throughout all ten production lines
Solder Paste: Koki SE48-M955 Type 3
significantly reduced setup and changeover
Stencil No: A48959V
time and resulted in a return on invest-
Stencil Thickness: 100 micron
38 – Global SMT & Packaging – March 2009
www.globalsmt.net
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