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Volume 6   Issue 6                July  2005


Battling Bottlenecks
How One Manufacturer Revolutionized its IG Production
by Jim Blamble

When I think of bottlenecks, I usually think of how long they are, not how to decrease them. However, necessity is the mother of all invention. Window fabrication personnel, especially plant engineering and management, often attempt to decrease the labor component of window production in hopes of improving operations.

It is rare to develop a plan that can both decrease the labor component and increase throughput. It is more likely that adding employees to a given line will increase throughput. Unfortunately, this does not always guarantee an improvement in labor efficiency and the subsequent decrease in cost. Natural inefficiencies may occur when personnel is added to a line that was designed to accommodate a smaller number of employees originally. 

A Quandary for MI Windows and Doors
MI Windows and Doors of Smyrna, Tenn., which is owned by MI Windows and Doors, faced this dilemma. Increased demand had maximized the company’s production on its two glass lines. The company had two options: adjust operations by changing insulating systems and implementing a new line or lines or create a new concept in insulating glass unit (IGU) production.

To better understand its machine limitations, the company reviewed the various cycle-times involved in its current insulating glass unit (IGU) production by conducting time studies of the following stations:

• Glass feeding to the washer;
• Glass washing and delivery to the IG room;
• Glass dealing;
• Flexible spacer applications;
• Glass topping and muntin insertion;
• Heating and pressing IGUs; and
• Sealing and offloading IGUs.

What They Found
The time studies revealed that the production bottleneck was in the muntin insertion and glass topping station. The next slowest cycle-time, less than 20 seconds, was found in the spacer application stage. If the company was able to perform muntin insertion and glass topping in less than 20 seconds, throughput could sky rocket.

Bringing these two cycle-times into symmetry would net 1,350 IGUs in a 7.5-hour shift at one application station. With the company’s two application stations, the resulting net IGU production would reach 2,700—on paper.

From Paper to Reality
What looks good on paper may not always be the most practical solution when it comes to implementation. If the company could adjust the cycle-time at the muntin insertion and glass topping station to match the spacer station cycle-time more closely, could the company keep up with the new demands such as supplying enough cut glass, offloading enough completed units and having enough fabricated muntins ready for insertion? Challenges, such as these, arose in the concept that caused MI Windows and Doors to work even harder at finding the most efficient solution.

Dual-Chamber Topping Table
Ultimately, the company closely matched the cycle-times at the two stations by splitting the function of glass topping and muntin insertion into two distinct functions at one gridded surface airfloat topping table. This table has a dual chamber that allows muntins to be inserted (or loosely inserted at the flexible spacer station) and squared by one employee, while another employee tops units with the mating glass. The company discovered that, with these tables, the cycle-times could be congruent with the two previous stations at less than 20 seconds. 

TruSeal Technologies and MI Windows and Doors worked together to create the dual-chamber topping table. In particular, MI exerted an extraordinary effort by taking the on-paper concept and turning it into a reality. To make the system work, the company had to analyze all aspects of the process including production paperwork, cut glass inventory, muntin inventory and having ample production and storage space for the increase in completed IGUs.

Adding the dual-chamber topping tables increased production from 1,400 mostly gridded IGUs per day to 2,700 IGUs or more per day. The production increase resulted in the addition of two employees at the muntin insertion stations and one extra employee at the offload area to handle the increased throughput (See Figure 1, page 10). 

In summary, MI Windows and Doors has increased throughput by approximately 1,300 IGUs per day by adding three employees to the line and a minimal capital expenditure for the dual-chamber topping tables. The costs of the tables are dependent upon the size of surface space required and tilting requirements, most dual-chambered topping tables currently cost less than $20,000 USD. Units per man hour (UPMH) dedicated to the IG line increased (based on 8 hours of pay/7.5 hours of productivity), resulting in an increase of 35 percent with no major IG line layout or system changes. 

Jim Blamble is the U.S. national sales manager for TruSeal Technologies Inc. based in Beachwood, Ohio.

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