Process control parameters impacting foam garage door panel manufacturing

The foam that makes up the core of many modern garage doors is possible thanks to some very specific chemistry.

But solid chemistry alone is no guarantee for success.

Optimal processing conditions must be maintained to produce quality panels. If they’re not, common quality problems such as underfilling, overfilling or an array of surface defects can result.

Many foam garage door manufacturers experience unacceptable scrap rates which occur because the process parameters discussed below are not appropriately controlled. But with a better understanding of these parameters — and how they relate to one another — manufacturers can become key front-line troubleshooters that save time, money and material.

Know the 4 main process control parameters

In foam core garage door manufacturing, four main process control parameters impact finished product quality:

  • Temperature (including storage, processing equipment and ambient)
  • Dispensing rate
  • Line speed (in continuous applications)
  • Demold time (in discontinuous appplications)

While determining ideal process control parameters begins during process design, we’re not going to talk about specifications at any length. This resource is meant to help you understand the things you can control right nowwithout going back to the drawing board.  

A picture of several bulk storage tanks for foam inside a factory.

Temperature

Temperature might be the most difficult process parameter to control because it impacts foam garage door panel manufacturing quality at a few different stages. 

Bulk storage – The two components of a foam system are usually stored in large tanks in ambient conditions. Bulk storage temperature is easier to manage if the tanks are inside a climate-controlled facility. But if facilities lack climate control or the tanks are kept outdoors, the foam components are at the mercy of frequent seasonal and daily temperature fluctuations. As temperature deviates more and more from the ideal processing range, operators’ options for correcting the problem by tweaking other process parameters significantly diminish.

Day tank storage – Prior to mixing and dispensing, foam components are kept in “day tanks.” Most modern equipment features heat exchangers in these tanks designed to regulate the temperature of the foam. But if the components enter the tanks too hot or too cold, the heat exchangers won’t do their job in time. If precursors are dispensed outside of their normal process temperature, they might not mix or dispense properly. 

Processing equipment – For garage door panel foam to cure properly, the temperature of hardware such as platens, molds or conveyors must be maintained according to the foam system’s specifications. If contact surfaces are too hot, foam could cure before reaching its full rise. If they’re too cold, the foam could cure to a gummy texture and pull away from surfaces it should stick to. 

Ambient – If facilities lack climate control, seasonal or daily temperature fluctuations could cause quality problems that operators must constantly work to correct. A lack of ambient temperature control could exacerbate quality problems if the other temperature parameters noted above also are not well-controlled. However, if the other temperature parameters are well-controlled, ambient temperature is less of a factor in product quality.

Dispensing rate

The amount of pour-in-place foam deposited from a mixing machine to a mold or conveyor platen can influence its expansion and curing. This rate is settled on the premise that other parameters (such as line speed, demold time and temperature) also are optimized. A common misstep is for manufacturers to observe defects like voids or underfilling in finished panels and crank up the dispensing rate in response. 

That might be the right answer, but it might not. Was the temperature of the foam components or equipment too hot or too cold? Was the line speed too fast or demold time too brief? 

Line speed

That same logic applies to line speed for continuous panel manufacturing. This speed is determined in advance in harmony with other process parameters and the foam’s curing characteristics. 

If line speed increases without a commensurate increase in dispensing rate, there won’t be enough foam applied to fully fill panels and underfilling will result. Even if dispensing rate is adjusted to match a faster line speed, higher speed could result in foam that never fully cures. 

Conversely, if line speed slows, too much foam could be dispensed onto the conveyor unless the dispensing rate also is dialed down. Lower speed could also extend the curing time beyond what a foam system requires, potentially resulting in over-cured foam. 

Demold time

Demold time — which refers to the amount of time foam is held in a fixture to cure — is the discontinuous manufacturing version of line speed. Essentially, the same problems described in the line speed section can occur if demold time is adjusted upward or downward.

A picture of a variety of bulk storage tanks and smaller totes for foam inside a factory.

Take a holistic approach to troubleshooting

Foam garage door panel manufacturing is a complicated process where many variables must be tightly controlled. They must also be collectively optimized.

Fortunately, most quality problems can be solved by making educated process parameter adjustments. It’s merely a matter understanding the why behind a problem. 

But if problems still persist, the technical support and product guidance offered as part of our high-service business model is just one reason why a relationship with Foam Supplies is different. Are you experiencing persistent quality issues? Are process parameter adjustments not helping? It might be time to get some help. Contact a technical expert here

Case study: Investigation reveals sources of persistent garage door foaming problems

The mark of a good partner is their ability to listen to a customer’s challenges and identify the most appropriate action to address it.

But a great partner understands complex processes and can help untangle the knot of problems that arise when those processes are not performing.

In this case, our customer was one of North America’s premier garage door manufacturers. They initially approached Foam Supplies after researching alternative blowing agents to meet new regulatory standards.

To ensure their discontinuous garage door manufacturing operation utilized foam that complied with global environmental accords, the customer chose to adopt a polyurethane foam blown with our patented Ecomate® technology.

However, during the initial engagement our technical service rep (TSR) noticed quality issues with the panels being produced with the incumbent foam system that would overshadow any benefits expected from implementing the new FSI foam system. An intensive investigation ensued to find the root cause of the quality issues.

Problem #1 – Inadequate dispensing pattern

Our customer was initially only interested in switching to a new foam formula with a compliant blowing agent. They wanted a simple drop-in replacement. Assessing the manufacturing process was not on the table — at least, not at first.

However, during the consultation process our TSR noticed overfilling, underfilling and visible defects including voids, waves and dimples in finished foam panels. He knew that changing the foam system alone would not solve the quality problems.

A picture showing the dispensing of foam onto a garage door shell during garage door panel manufacturing.

The TSR first observed that dispensing the foam in the panels at only one location was a major cause of the problems. Comparative tests had demonstrated that the FSI foam system had greater flowability than the competitive material, but because of the length of the panels, the expanding foam was not able to completely and uniformly fill the panels before it cured.

When the process engineer responsible for the operation followed the recommendation of the TSR to inject the foam at multiple points the foam completely filled the panels more uniformly and without voids.

But while changing the number of injection locations made a noticeable improvement, it did not completely solve the quality problems. As our TSR dug deeper into the customer’s process, more causes were uncovered.

Problem #2 – Incorrect pumps

The two components of the foam system are stored in large bulk chemical tanks and transferred to the panel manufacturing operation using gear pumps, which are specified by pressure and flow rate.

During his investigation, our TSR noticed that the existing pumps were too large and were operating at flow rates below their design specifications. The result was that the flow rates were inconsistent and unable to be controlled.

In other words, it was as if they were trying to adjust the output of a fire hydrant to properly feed a garden hose. It couldn’t be done  

The fix was simple — swap out the pumps with smaller ones that were matched to the desired dispensing rate.

Once installed, the new pumps  made a big difference. But the problems were not entirely solved for the customer. 

A close-up image of a foam-filled garage door panel in a factory.

Problem #3 – Lack of temperature control

The temperature of materials and equipment involved in foam panel manufacturing have just as much impact on product quality as any other process parameter. 

For best performance, manufacturers need to control the temperature of the following:

  • The ambient temperature within the facility itself
  • The large storage tanks that feed the A and B components to the dispensing machine
  • The “day tanks” on the foam dispensing machine 
  • The foaming fixtures that control the surface temperatures while the foam is rising and curing

Polyurethane systems mix, dispense, flow and cure best within the temperature range specified by their manufacturer, so controlling those temperatures that variable is key. 

Controlling the temperature in day tanks and on panel surfaces is most critical. The storage tank and ambient temperatures can impact how well day tank temperatures are regulated. 

Unfortunately, because the manufacturing equipment dated from the 1990s and had not been well maintained, it lacked the temperature control capabilities needed to compensate for widely variable ambient temperatures.

A close-up cross-section picture of four foam-filled garage door panels stacked one atop the other.

Starting from scratch

There were too many problems. The time, effort and expense required to Frankenstein the old equipment back into shape was more than the customer could stomach.

The customer agreed with our TSR that the only solution at that point was to install a new line. The TSR provided guidance on specifying new equipment that addressed at once all the problems revealed in his investigation.  

This was an extreme case where a lack of process control plagued almost every aspect of this customer’s garage door foaming operation. Worse, the customer didn’t realize they had such serious problems.

Thanks to the knowledge and guidance provided by our TSR, the efficiency, consistency and quality of our customer’s manufacturing process have increased.

Such close support is uncommon in the industry, but it’s a cornerstone of how we do business.

Have a problem you want to run past our technical service staff? Get in touch with a rep here.