Additional operations

Heat treatments allow the structure of the metal to be changed to achieve the required hardness properties. At Polydec SA, we carry out some of these heat treatments in-house, and subcontract others to our certified partners.

Tempering and hardening
In most cases, heat treatment/tempering is necessary for several reasons:

• reducing mechanical wear
• increasing the useful life of the part
• avoiding problems of deformation during assembly
• guaranteeing functionality (for example for test probes)

The steel's hardness is obtained by heating the workpieces to a temperature of between 800 and 1000 °C, and then quickly cooling them. This treatment makes the steel harder, but also more brittle. To achieve a good compromise and reduce brittleness, the workpieces are heated a second time to a certain temperature that depends on the desired hardness. This stress relief is called "tempering".

For these treatments, at Polydec SA, we use trusted specialist partners who complete their tasks in line with the strict quality criteria that we impose.

Structural hardening
As in traditional hardening, structural hardening involves increasing the mechanical strength of the workpiece. This process is used, for example, on specific alloys such as CuBe, Arpal and palladium alloys (not compatible with steel).
The workpieces are heated to over 300 °C for approximately 2 hours, then slowly cooled, increasing their hardness.
These treatments are performed exclusively in our workshops.

Carburization
The carburization process enriches the carbon content of the workpiece's top layer. This process involves the diffusion of carbon dioxide gas for several hours at temperatures of between 900 and 980 °C.
Structural hardening can then be performed.
Carburization thus enables the peripheral layer of the workpiece to be hardened while retaining the characteristics of the steel. The workpiece becomes resistant to wear and friction, and its brittleness is reduced.
For these treatments, at Polydec SA, we use trusted specialist partners who who complete their tasks in line with the strict quality criteriathat we impose.

In chemical polishing, the workpieces are dipped in an acid bath to remove roughness, burrs and other surface defects. The thickness must be increased prior to treatment.

This process is highly effective for treating all hard-to-reach areas. However, it is not suitable for all types of workpiece, such as tips, as it rounds ends and corners.

For these treatments, at Polydec SA, we use trusted specialist partners who complete their tasks in line with the strict quality criteria that we impose.

Sandblasting and microblasting involve blasting sand or microbeads (for more fragile surfaces) at high speed onto the surface of the workpiece. This process, which involves compressed air, is used for deburring, cleaning or for aesthetic purposes. Different effects can be achieved depending on the parameters used (grain size, air pressure, etc.).

Certain workpieces require galvanic treatments to protect or decorate sections.
Galvanic treatments use chemical baths to apply a metal coating to the workpiece:

• nickel plating
• gold plating
• tinning
• rhodium plating

The aim of these operations is to protect the workpieces from oxidation and corrosion. In the watchmaking industry, these treatments allow an aesthetic touch to be added. In the electronics industry, this is used to improve electrical conductivity, enabling the signal to be better transmitted.

Other chemical treatments can also be applied to protect the workpieces from oxidation, but without adding other materials. These include:

• passivation
• epilame

For these treatments, at Polydec SA, we use trusted specialist partners who complete their tasks in line with the strict quality criteria that we impose.

Frosting is a surface finishing process used to create a rough surface on a workpiece. Created exclusively by us, theaim of this process is to enable the fitting or better adhesion of an overmoulded plastic part.

This operation can be performed in one of two ways:

1. directly on the turning machine, enabling time and cost savings
2. secondary operations on finishing automatic machines developed and designed internally and offering the following advantages:

• almost the entire length of the workpiece can be frosted
• less workpiece deformation
• more pronounced recesses since the process is performed as a final operation (including hardened workpieces)

Whether performed directly on the turning machine or as a secondary operation, this finish is obtained by crushing with diamond-tipped tools. For secondary operations on large volumes, we have developed our own machines internally, creating a dedicated finishing department.

Sunray polishing is a decorative secondary operation that gives the appearance of the sun's rays on the flat surface of the workpiece.

The workpieces are placed in a rotating fixture. The "rays" are created using a spindle rotating in the opposite direction to the workpiece and producing straight lines that pass through the centre.

This treatment is performed exclusively in our workshops.

Rolling is a secondary operation consisting of polishing and hardening the surface of the pivots on a part within very strict tolerances.

The part is positioned in the semi-circular "target" notches. It is rotated using a gear- or friction-driven device. The pivots are strain-hardened as they are crushed by the hard metal bell-shaped wheels. Depending on the case, any burrs can be removed with micro-polishing.

The aim of this operation is to reduce friction and increase the surface hardness of the part, thereby extending its lifespan.

Polishing is a flat grinding process performed on the surface of the workpiece to remove any traces of machining (turning, milling, etc.)

This operation can be performed prior to bulk polishing to obtain a smooth, flat finish. It is also an essential step in preparing for black polishing.

Black or mirror polishing is a finishing operation that creates a mirror effect on the surface of the workpiece (e.g. eccentrics, screw heads, etc.). In general, these components are the visible parts of the watch movements used in fine watchmaking.

The workpieces are placed in perforated plates and glued using gum lacquer. These plates, which rotate around their own axis, are then rotated in the opposite direction on a lapping machine (tray) to perform a double rotation. An abrasive liquid must be applied between the workpieces and the lapping machine to obtain a mirror polished effect.

Finally, the workpieces are cleaned using special solvents to remove any residual glue.

For these treatments, at Polydec SA, we use trusted specialist partners who complete their tasks in line with the strict quality criteria that we impose.

Bluing involves deliberately oxidising steel workpieces by heating them to over 290 °C. The aim of this operation is to give them a blue colour for aesthetic purposes, e.g. for watch movements, and also to increase their corrosion resistance.

For these treatments, at Polydec SA, we use trusted specialist partners who complete their tasks in line with the strict quality criteria that we impose.

PVD technology is used to apply a fine coloured layer to the workpiece for aesthetic purposes, while retaining any previous surface treatments.

This layer is applied by sputtering, at a temperature of between 100 and 150°C.

This technology is used in particular to decorate parts used in luxury items.

For these treatments, at Polydec SA, we use trusted specialist partners who complete their tasks in line with the strict quality criteria that we impose.