The goal of this thesis work has been to describe the product requirements and process methods for manufacturing steel tube car seat frames. A wire frame is commonly used in the seat padding in the back seat of a car. The wire frame currently consist of wires with dimensions 4.5 mm and 6 mm. The frame is responsible for:

 Fastening the seat in the back seat of the car (keep it in place during e.g. impact),

 Serving as a point of attachment for upholstery,

 Keeping the shape of the moulded goods

The main goal of the report was to present a viable solution based on the following objectives:

1. Find a standardized tube, which corresponds to the current frame and meets all the stated requirements in the problems description,

2. Define the minimum bend radius of the intended tube dimensions,

3. Investigate suitable method of joining the tube parts while maintaining the strength of the frame

A viable solution is presented, consisting of two tubes with customized dimensions:

 6 mm OD x 0.5 mm wall thickness will replace the 4.5 mm wire,

 7 mm OD x 0.75 mm wall thickness will replace the 6 mm wire

This solution results in a weight reduction of 47 %, fulfilling the requirement stating that: 'The weight of the new frame should be approximately 50 % of the current frame weight'.

The solution presented is 27 % more expensive, but the increased cost could be financed by the automotive industry's willingness to pay for reduced weight.

The tubes have a theoretical minimum bend radius of 3 x the outer diameter of the two tube dimensions respectively.

The tubes will be welded using projection resistance welding. This method is currently used welding the wire frame. The current machinery will be adjusted to work with the defined tube dimensions.