Get in Line
Inline Assembly Techniques
for Patio Doors, Picture Windows and Mulled Units
by Ken Nekola
Window manufacturing has seen a rapid development of new materials and manufacturing processes in the past decade. With the advent of vinyl window/door frames and components, manufacturers have been confronted with an ever-increasing selection of automated machinery to optimize, cut, square, fasten, weld and clean vinyl parts. Investment in vinyl processing machinery has been staggering, but it has provided the window and door manufacturer with increased efficiencies, reduced labor content, reduced scrap and improved product quality.
Likewise, new insulating glass (IG) spacer systems and automated IG assembly processes have experienced similar interest and investment, resulting in lower production costs and improved product
An Overlooked but Crucial Area
While this heightened attention has been drawn to specific areas of the manufacturing plant, final window assembly has often times been overlooked. Inefficient and labor-intensive final assembly can erode the benefits gained from improved vinyl processing, glass handling and IG assembly. In a relatively modern window plant that has spent hundreds of thousands of dollars on state-of-the-art automated vinyl and IG machinery, it is not uncommon to see window and door assembly equipment literally cobbled together out of two-by-fours and glue. The assembly area often has the appearance of an anthill after kicking the top off.
One recent plant visit revealed a home-made “large unit stretch wrapper” that involved two laborers holding the large, finished unit upright on a modified wooden wire spool, while a third ran circles around the unit with a hand stretch wrap applicator. Not only did this operation require three laborers and have a very slow cycle time, but the person applying the stretch wrap was wearing out his safety shoes on one side because he didn’t have the foresight to run in opposite directions alternately.
In these instances, the final assembly process has evolved over a period of time and consists of a cluster of fragmented and separated operations with a combination of stand-alone horizontal and vertical workstations. This “evolution engineering” of the assembly process results in excessive floor space utilization, increased product handling, unsafe working conditions and high labor content. Assembly laborers often finish their shifts exhausted from excessive manual lifting and carrying of work-in-process from station to station. Operator fatigue can be traced back to the cause of on-the-job injuries, damage to work-in-process, errors in assembly and inconsistent quality.
Developing an Integrated System
As manufacturers continue to look for ways to streamline operations, reduce costs and improve competitive positions, the final window assembly process deserves a closer look. In addition, a new trend has developed that will force manufacturers to revamp assembly processes sooner rather than later. Residential and commercial new construction is requiring more large window and patio door units. Large window units are incorporating multi-floor picture windows and mulled sections with large shaped top transoms, while patio and French door assemblies are using more and larger panels. Due to the increased sizes and weights, a fragmented assembly process with unsafe equipment, relying on manual lifting and carrying, will not be feasible in the future.
Rather than an afterthought, window and door assembly should be approached as a complete, integrated system. The goal should be to provide a logical progression of in-line assembly stations that minimize handling, especially lifting and carrying.
Don’t Do it Yourself
Once the window manufacturer understands the system approach to window assembly, a big mistake commonly made is to attempt to design and build the system in-house, with its own resources. The rationale behind this reasoning is that the company can save money by “doing it itself.” More often than not this approach backfires, leaving the manufacturer with a less than optimum system, at a higher than realized cost.
Some issues involved with this do-it-yourself approach that make it a less than wise decision include:
• In-house personnel have only their own experience to derive solutions from. While they may be highly competent technically, they may spend a lot of time re-inventing the wheel, or waste time implementing solutions that have been disproved by others.
• True cost of systems and equipment made in-house are often grossly underestimated. First, the actual time spent on the project is generally underestimated and not truly accounted for. Second, actual costs of the resource man-hours are frequently under-stated or not accounted for at all. There is a tendency for technical managers to rationalize that, “since they have the resources available anyway, their time is free.” Nothing could be further from reality.
• In-house resources should be concentrating on the manufacturer’s main business: making windows, not on making equipment and processing systems.
• In the long run, this approach generally costs more, not less, since the system, and resulting on-going cost savings, likely will be less than optimal.
The Answer to Your Assembly Solutions
The following companies are just a few offering equipment used for the assembly of windows and doors.
Team up with a Supplier
If in-house design and build is not a wise direction, what better alternatives exist? The best solution is for the window company to team up with a reputable manufacturer of window assembly equipment that has a documented history of providing turn-key, custom-engineered assembly systems. Such suppliers can draw from years of exposure to good and bad ideas throughout the industry and can propose an optimum system quickly that is custom configured for a specific and unique assembly process. The supplier will then take on total system responsibility; assuring the system will meet pre-determined performance specifications. This eliminates the typical finger-pointing and excuse-making when single-source responsibility is not assigned and system performance is less than anticipated.
When selecting an equipment manufacturer to supply a custom-configured, in-line, turnkey large-unit assembly system, what factors should a window company consider? Once the window manufacturer commits to upgrading its large unit assembly system, the next, and possibly most critical decision is choosing a single-source supplier. Here, the window manufacturer is looking for something beyond just an equipment supplier or manufacturer’s representative. While there are some suppliers that offer pieces and parts associated with window assembly equipment, not all are competent to custom engineer turnkey systems. When considering a supplier, these qualifications should be made:
1. Competent suppliers will have their own in-house design engineers, field service assistance technicians and fabrication shops. Suppliers that merely farm out design and fabrication generally don’t have the capability to integrate systems.
2. Competent suppliers will have a documented history of providing turnkey, integrated systems. Drawings, photos, videos and personal references should be available to demonstrate the extent of work done in the past.
3. A competent supplier will have an obvious understanding of large-unit assembly so it can tailor a system for each unique application. It can act as a knowledgeable consultant in the field of large unit
4. In order to minimize the overall system price, the supplier should have a large selection of standard, pre-designed, in-line assembly components that can be configured into custom assembly lines. Some typical components include, but are not limited to: frame conveyors, clamping assemblers, power raising stations, lift assist glazing devices, backlit inspection stations, tilting mull assembly tables and vertical in-line stretch wrappers.
Other Assembly Trends
Specifically regarding in-line, large-unit assembly systems, some trends are worth noting. The overwhelming preference is for assembly systems that allow for predominantly vertical movement of units from station to station. Vertical lines require less floor space and get the work up in the operator’s face where it is seen easily and reached (no bending over horizontal tables). This is accomplished with a full-length roller conveyor that can accommodate nail fins, J-channels and other structural members without risk of breaking. Where assembly operations do require horizontal orientation (mulling for example), in-line power tilting tables should be incorporated to eliminate lifting and carrying. Lift-assist devices are being utilized for large-panel glazing, allowing a single operator to glaze large panels quickly and safely that otherwise would require two people manually lifting and placing the IG. For final packaging, in-line vertical large unit stretch wrappers are being used increasingly, that have inbound and outbound roller conveyors. These unique wrappers are designed to handle large, heavy assemblies and even shaped transoms. With proper component selection, it is feasible to configure a complete large unit assembly system that eliminates lifting and carrying throughout the entire assembly process.
Ken Nekola serves as national sales manager for Machine Techniques Inc. in Aurora, Ohio.
© Copyright Key Communications Inc. All rights reserved. No reproduction of any type without expressed written permission.