The MOLD’n SEAL process

 

Combination of injection molding and foam sealing

Sonderhoff developed the MOLD‘n SEAL process – the combination of injection moulding with mixing and dosing machine in one production cell – in cooperation with Arburg and Engel, the manufacturers of injection moulding machines.
After the injected part is taken out of the moulding form, it is directly applied with the Fast-Cure sealing FERMAPOR® K31, a polyurethane foam especially developed for the MOLD‘n SEAL procedure.

In the MOLD‘n SEAL procedure the two formerly separated processes injection moulding and foam gasket application can now be combined in one production step with regard to efficiency and product quality. The injection moulding parts no longer need to be prefabricated and stored temporarily as before.

With MOLD`n SEAL the following saving potentials can be realized:

  • By a faster curing time of the Fast-Cure seal material (tack-free after 120 sec.) an accelerated further processing is possible.
  • Instead of two only one handling robot for the part handling of both processes (injection moulding and foam gasket application) is necessary.
  • Through process integration injection moulding machine, six-axis handling robot, mixing and dosing system and discharge conveyor belt need only a very small footprint of just 24 to 40 sq. m. depending on the different format of each configuration.

MOLD`n SEAL process procedure:

The still warm injection moulded parts are taken out of the mould by a six-axis robot and placed under the mixing head MK 600 of the Sonderhoff dispensing machine DM 402/403 which then applies the foam sealing material accurate to the contour of the part.


The polyurethane Fast-Cure sealing system from the product family FERMAPOR® K31 is cured significantly fast, additionally promoted by the residual warmth of the just injection moulded part.

Already shortly after the foam gasket application the handling robot positions the part on the conveyor belt for further processing.

The MOLD`n SEAL process can be adapted to different cycle times of injection molding and to parts with various geometries and mould cavities (one- to four-fold tools) for direct foam sealing. Additional processes like pre-treatment of the plastic part’s surface by ionisation or plasma treatment can also be integrated.

Automation with Engel

With the MOLD‘n SEAL process housings for moisture-proof lamps by Zumtobel Lighting are injected moulded on a hydraulic ENGEL machine, the victory 1350/300 tech series, and immediately afterwards applied with a Fast-Cure polyurethane sealant bead in the seal channel of the housing. This foam sealing from the Sonderhoff product line FERMAPOR® K31 is mixed and dosed by the mixing head of the dispensing machine from Sonderhoff.

More than 523 lamp housings could be produced in an unbroken eight-hour shift. Within 55 seconds per production cycle the components were injection moulded, removed from the mould, foamed and placed on the integrated discharge belt for curing and further processing.

Process details

The housing of the moisture-proof lamp is removed from the injection moulded system using the ENGEL easix robot and stored in a holding and cooling position. Then, the robotic arm takes a cooled part, guides it past the ionisation station to the MK 600 mixing head of the Sonderhoff mixing and dosing system and positions the seal channel of the housing directly under the mixing head dosing nozzle.

The multi-axis robot is programmed in such a way that it scans the part contour two times, whereby the dosing nozzle of the MK 600 applies the polyurethane sealant precisely on the basis of the seal channel which is just a few millimetres wide. The discharge performance is just 0.45 g/s per application cycle of total two material layers dosed into the seal channel. After placing them on the discharge conveyor belt, the injection moulded part cools down and the foam sealant is tack-free within two to three minutes. This makes it possible to further process the part after a brief period of time.

Material

The rapid-reaction 2-component sealant material from the FERMAPOR® K31 product family, which was specially developed by Sonderhoff for the MOLD’n SEAL procedure, can bridge a mixing head waiting period of 25 seconds.

In this time, the robotic arm picks up a new injection moulded part from the tool, places it in the cooling position, and removes a part that was already there, guides it past the ionisation station and begins the sealant application afresh with its position under the mixing head.

Automation with Arburg

With the MOLD‘n SEAL process more than 2,500 back cap parts were injection moulded on a hydraulic injection moulding machine from Arburg, type Allrounder 570 S with 2.200 kN closure force and a 4-fold tool, during an eight hours shift.

Directly afterwards the polyurethane based foam sealing Fast-Cure from the Sonderhoff product line FERMAPOR K31 was applied in the seal channel of the parts.

Process details

The process in details: Within a cycle time of 45 sec. four parts are injection moulded, taken out of the four-fold mould with a 6-axis handling robot, seal foamed thereafter and transferred on the integrated discharge conveyor belt for curing and further processing.

The multi-axis robot is programmed in such a way that the mixing head MK 600 is moved accurate to the part contour so that the dosing nozzle can place the foam gasket material into the seal channel. The discharge performance is 1.17 g/s. The handling robot hands over the parts to the transfer station of the production cell which places them on the discharge belt. The foam gasket becomes tack-free within 2 to 3 minutes and can be further processed after short time.

Material

The rapid-reaction 2-component Fast-Cure seal material from the FERMAPOR K31 product family is adapted to the injection moulded cycle that it can bridge a mixing head waiting period of 18 seconds. During this time, the robotic arm picks up new back cap parts from the injection mould, holds them under the mixing head, scans the contour of each of the four parts and applies the foam gasket into the seal channel.

After handing them over to the transfer station the back cap parts are positioned on the assembly line for curing and further processing, and the foam sealing application process starts again.