THE One-Shot® Window Frame is the patented pending car part that got sapa on the podium with ford and general motors at the spe Automotive TPO Conference 2017 in Detroit: it was awarded among the best innovations of the year and it requires investments that are up to 3 times lower than for the traditional methods.

Today I would like to talk to you in detail about one of our patented pending parts: The One-Shot® Window Frame. And the reason for this is simple: I am certain that this innovation can help you a lot in your work and it can bring advantages not only in economic terms but also in terms of product quality.

Do you not believe me?

Let me try to explain what it is all about.

The idea to find a solution stems from the desire to eliminate some issues that are typical of car parts hollowed with gas – you may know what I’m referring to, but allow me to list just a few of the issues:

  • Deformations: during cooling, deformation can reach or even exceed 3mm or 3.5mm;
  • Aesthetic issues: when you join deformed parts on the car, unpleasant aesthetic defects are created;
  • Difficulties in making the part more lightweight while also reducing production costs;
  • High investments for equipment.

The perfect occasion was when we were asked to produce the Window Frame for the tailgate of Volkswagen Arteon (or Passat CC), a very elegant 5-door sports coupé car.

When we were asked to find an innovative solution that could once and for all resolve these issues, we realised that costly and conspicuous investments were not the best answer. The very equipment to hollow parts with gas is very costly and we didn’t like the idea of responding in the same old way out of convenience.

We needed a different approach, a new way to achieve the result. We wanted to come up with our very own solution.  

As you well know, in the traditional method, after injecting the molten plastics into the part mould, nitrogen is also injected in order to hollow out the part. This technique is consolidated, and it is often used to create the door’s handles, but this technique was never really updated.

The nitrogen flux injected in the mould empties out the cylinder with the plastics and the plastics is then left to harden, in a process known as thermosetting. This cooling process brings however, severe issues in terms of deformations, especially for the rear windows.

Imagine: so much effort and so much work, and then you realise that the excessive deformations on the part cause enormous joining problems. It is very frustrating.

In this scenario, SAPA’s engineers decided to deploy the One-Shot® Method, which was created precisely to optimise processes and costs, while keeping high quality standards. The One-Shot® Method as a matter of fact, is the only method that allows you produce car parts with:

  • Less weight;
  • Better cost efficiency;
  • High quality standards.

The attention of the Innovation Engineering department, which is the place where the most ingenious intuitions are turned into concrete solutions, was focused on optimising the whole procedure and reducing the cost of the entire process, while also obtaining further important advantages for the client.

Hence the Window Frame produced with the One-Shot® Method is different: it uses a thermoplastic cooling process.

What is innovative is the presence of a small perforation that allows for the part to be hollowed out and cooled out, avoiding deformations and in shorter time. The air does not go to the nitrogen unit but in the channel, and it hence flows out of the piercing that was created.

The inside is then cooled with air and not with water. In this way, you have smaller deformations (around 1mm).

I want to be honest with you: it wasn’t an easy path.

Creating the piercing requires a thorough study of its positioning. The risk is that, when the air is blown in, the molten material goes into the channel of the jack and obstructs it.

However, we were able to solve this issue by moving the piercings to an area with less molten material and by recalculating the space between the channel and the pin inside the piercing.

It is a pin inside which the air then needs to flow.

And this is no trivial detail.

As you know, deformations cause very unpleasant consequences:

  • Issues when putting together and joining the pieces;
  • Aesthetic issues because the pieces could not be joined perfectly;
  • Noise issues because the pieces were not joined perfectly.

If deformations are less than 1mm, these problems are small or even non-existent and the effort in your work no longer brings frustration but satisfaction. Not bad at all!

I take it you are wondering how much such a solution may cost, considering its extraordinary nature.

We took this aspect in consideration, too.

Because, while it is true that a One-Shot mould costs 10% more than traditional ones, it is also true that the overall investment is three times less than in the traditional method.

And this is not all:

  1. Parts produced in this way are 8% lighter than with the traditional method, hence you can reach the objective of lightweighting the car;
  2. You can mould in one piece what you would mould in 3 different pieces, hence the quality perceived inside the car is higher.

This part is already industrialised by Volkswagen and in 2017 it was among the 5 best patents awarded at the Automotive TPO Conference organised by the Society of Plastics Engineers.

Here is a brief summary of the results we achieved with this part:

  1. Components are 8% lighter than in the past, so you will reach the objective of reducing the car’s weight;
  2. 10% costs savings on each part, which will allow you to have important cost savings on the whole process;
  3. Totally improved production cycle, so with just one mould you get something that you would normally need 3 moulds to get;
  4. Deformation reduction by 300%
  5. Improved luxury sensation thanks to less rubbing and noise. 

We regard this as a small and yet huge achievement.

Kind regards,


Giovanni Affinita,

Executive Director and Member of the Board of Directors at SAPA

if you would like to solve the deformation and joining issues of plastic parts and receive more information on the one-shot® method, fill in the form below.

we’ll get back to you within 24 hours!

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