CUPAL Installation and Processing Guide

The CUPAL bimetal composite is processed much like working with pure copper. This guide summarises the most important processing methods, installation tips and the limits you must observe.

What processing do we offer?

As the Hungarian distributor, Hidramix Kft. typically handles the following processing steps in-house:

• Custom cutting from CUPAL sheet (discs, strips, rings, rectangles, custom contours)
• Drilling (bolt holes)
• Simple cold-forming by arrangement

For more complex work (deep drawing, roll forming, high-volume runs with complex tooling, electroplating, soldering) the customer's own workshop or a subcontracting partner is the typical route — CUPAL is suitable for all of these, but we do not perform them in-house. The material-side options are summarised in the sections below.

Cold-forming options

CUPAL sheet can be processed with the full range of cold-forming methods. The submicroscopic intermetallic layer at the aluminium-copper interface allows forming without the layers separating:

• Bending (Biegen): Free bending and pre-bending
• Deep drawing (Tiefziehen): Forming more complex 3D shapes
• Embossing (Prägen): Pressed patterns and shapes
• Stretch forming (Streckziehen): Uniform thickness reduction
• Edge bending (Abkanten): Precise angular bends
• Roll forming (Profilieren): Forming continuous profiles
• Beading/flanging (Bördeln): Forming rims and beads
• Riveting (Nieten): Mechanical fastening
• Seaming (Falzen): Folded seams

During cold-forming the copper side faces outward and the aluminium side inward, so the composite follows the natural arrangement during the drawing process.

Cutting and drilling

CUPAL can be cut and drilled with most standard metalworking methods:

• Guillotine shear, waterjet, laser — all applicable
• Drilling: standard HSS bits, slower feed, starting from the aluminium side
• Edges: the cut-edge smoothness depends on the chosen method; our standard cut edge (GK) is burr-free and can be used directly in technical applications

Soldering guide

The copper side of CUPAL can be soft-soldered, exactly like pure copper:

• Standard solders and fluxes can be used
• The copper side must be used as the surface to be soldered
• The aluminium side cannot be soldered directly with a standard process
• The soldering temperature must not exceed 260 °C (see heat-treatment limits)

Electroplating and surface finishing

The copper side of CUPAL can be electroplated (coated electrolytically), just like pure copper:

• Nickel plating, tin plating, silver plating and other electroplated coatings can be applied
• The coating process is carried out on the copper side
• The aluminium side is protected by its own natural oxide layer

Heat-treatment limits

CRITICAL LIMIT: CUPAL may be heat-treated at a maximum of 260 °C for no longer than 4 hours!

This limit is the single most important parameter to observe when processing CUPAL:

Why does it matter?

• Exceeding the permitted heat-treatment parameters leads to uncontrolled intermetallic-layer growth at the aluminium-copper interface
• Uncontrolled layer growth degrades the joint strength
• An excessive intermetallic layer makes the material brittle
• The material properties degrade irreversibly

When is heat treatment needed?

• When excessive work hardening occurs during cold forming
• Heat treatment restores the material's formability
• Parameters: Max. 260 °C, max. 4 hours, slow cooling

Installation guide for CUPAL washers

Step 1: Surface preparation

• Clean the contact surfaces of the aluminium busbar and the copper cable lug
• Remove contamination and the oxide layer
• Do not use lubricants on the contact surface

Step 2: Checking the orientation

• Each face of the CUPAL washer goes against its own metal: the coppery, reddish face against the copper part, the silvery face against the aluminium
• The aluminium side (silvery, light colour) faces the aluminium busbar
• If the two sides cannot be clearly distinguished visually (e.g. due to an oxidised surface), they can be identified by light sanding: the reddish side is copper, the light, silvery side is aluminium. If sanding reveals no copper side at all, the part in your hand is not a bimetal: toothed copper-alloy transition washers are sold under the same name, and they have no copper side to orient

Step 3: Assembly

• Place the CUPAL washer between the cable lug and the busbar
• Tighten the bolt to the torque specified by the manufacturer of the material pair or the equipment (CUPAL itself has no prescribed torque — this is always determined by the specification of the bolt, the connector and the equipment)
• A spring washer may also be used if needed to maintain constant pressure

Step 4: Inspection

• Visually verify the correct position
• The washer must not protrude beyond the contact surface
• Check the bolt torque

Surface finish options

CUPAL sheets are available with various surface finishes:

Summary tips

1. CUPAL can be processed just like pure copper — it requires no special tools
2. Max. 260 °C / 4 hours is the heat-treatment limit — never exceed it
3. Always check the orientation before installation (each face toward its own metal)
4. The copper side can be soldered and electroplated with standard processes
5. Custom shapes can be formed with any cold-forming process

Questions about processing CUPAL? Request expert assistance!