CI Machinery: Seaming with Hot Air on a MW112


Happy New Year! Just because it’s a new year doesn’t mean we’re going to forget about our ongoing series covering all of Celina’s production machinery. This week we’re going to cover the main workhorse of our production floor – the Miller Weldmaster 112 Hot Air Cross Seamer.

Hot air is one of the simplest ways to get materials sealed together. Not nearly as intrusive as sewing (which leaves a series of holes in the material and call allow water permeation) or as labor intensive as RF welding (which necessitates a smaller work/sealing areas due to technical constraints), a properly calibrated heat seal creates a water-tight link between panels that is as strong as the base fabric.

Each seam is created with a combination of three variables: heat, speed, and pressure.


The hot air from a 112 machine is directed by the air nozzle in order to heat the material between the two layers being sealed together. This air melts the two adjacent layers, allowing them to combine when pressed together. Variations in air direction and heat level need to be changed in accordance with the environment (different temperature days, etc.) to make sure the proper amount of melt is achieved.


At the same location as the heat, the silicone wheel on the 112 presses the newly melted layers together, effectively combining the two into a single piece of PVC coating. This takes places (the heating then pressing) within an inch of each other to ensure that the pressure hits the material when it’s at its hottest.


Once the pressure and heat levels on the machine are in the right zone, adjusting the speed of the machine is a way to fine-tune its sealing ability. Moving the carriage at different rates adjusts how long the nozzle has to heat up stretches of the material. Slight variances can be the tipping point between too slow and burning your material, or too quick and not getting enough temperature before pressing the pieces together.

Without going too far into the basics of machine operation, the MW112 is capable of combining these three variables and creating a strong seam between fabric pieces. As each piece is added to the whole, a larger sheet is created that can receive finishing or moved on to other areas of the factory for additional steps in the manufacturing process depending on the product being worked on.

All of Celina’s employees are cross trained across our various machines, allowing us to ebb and flow with production requirements as needed. Training on the MW112, often the starting point for new hires, gives you a leg up on understanding the underlying processes that Celina uses to create the wide range of products our customers love. Looking for more on our machinery or processes? Gives us a call at (888) 324-0654 or stop by our main manufacturing campus for a tour of our facility! We look forward to it!