Hopp til hovedinnhold
Rolvsøy Metallindustri

Where the strength comes from — when casting alone is not enough.

Heat treatment

Gravity cast aluminium parts are heat treated here to raise tensile and ultimate strength. Pressure die cast parts normally cannot be heat treated.

Send tegning +47 69 39 20 50

Post-processing · aluminium

Heat treatment

A gravity cast bracket heat treated after casting gains substantially higher tensile and ultimate strength. That is often the difference between the part being castable at all and not.

Send a drawing

The principle

Why not every part can be heat treated

This is one of the most important technical relationships in the casting trade, and one of the least understood outside it.

A pressure die cast part contains trapped gas. The metal is injected so fast that air is entrained and stays in the section. That is rarely a problem in service — but heat the part in a furnace and the gas expands and lifts the surface into blisters. Pressure die cast parts are therefore normally not heat treated.

A gravity cast part fills calmly under gravity. Less air is entrained, and the part will take both a solution treatment and an age.

The consequence for you as a designer: if the part needs heat treated strength, the process is decided before you have finished drawing. It is gravity, not pressure — and the part should be dimensioned for gravity from the start, with heavier sections and different draft.

Suitability

When heat treatment is right — and when it only costs

Heat treatment is a separate process step with its own cost, its own lead time and its own scrap risk. Specify it where it does a job, not by default.

Heat treat when

  • The part is load-bearing and the strength requirement sits above what as-cast metal gives.
  • The part has to take fatigue — alternating load over time, not a single load case.
  • The drawing specifies the alloy in a defined temper, for example T6.
  • The alternative would otherwise be a heavier part in thicker section to reach the same strength.

Skip it when

  • The part is pressure die cast. Trapped gas expands in the furnace and raises blisters under the surface.
  • The part is in zinc. Zinc alloys are not heat treated.
  • The part is not load-bearing. A cover or a fitting that just holds something in place rarely needs it.
  • Tolerances are very tight and the faces will not be machined. Heat treatment can move the part.

Datablad

Specifications — heat treatment

The effect is documented in our portfolio. The cycle itself — temper, temperature, soak time — is not published yet.

Machine park

Processes in house
Pressure die casting (aluminium and zinc), gravity die casting, CNC turning, CNC milling, boring, heat treatment, blasting
Processes we do not have
Sand casting, toolmaking, anodising, powder coating
CAM software
Autodesk Fusion 360
Number of die casting machines
Available on request
Clamping force
Available on request
Hot or cold chamber
Available on request
Maximum shot weight
Available on request
Platen size and maximum die height
Available on request
Gravity casting stations
Available on request
Maximum mould size, gravity
Available on request
Melting furnaces and melting capacity
Available on request
CNC lathes
Available on request
Maximum turning diameter and length
Available on request
CNC mills
Available on request
Milling work envelope
Available on request
Boring machine
Available on request
Heat treatment furnace
Available on request
Blasting equipment
Available on request
Automation
Available on request
Machining operations
CNC turning, CNC milling, boring, tapping, sawing, grinding
Machining experience
More than 30 years år
Number of axes, milling
Available on request
Heat treatment applies to
Gravity die cast aluminium parts
Heat treatment — effect
Higher tensile strength and higher ultimate strength
Tempers we run
Available on request
Blasting
In house
Anodising
Via subcontractor — aluminium only, zinc cannot be anodised
Powder coating
Via subcontractor
Finishing subcontractors
Available on request
Die ownership
The customer owns the tool. We procure it, specify it for our machines and maintain it.
Typical tooling cost
Available on request
Die life, aluminium
Available on request
Die life, zinc
Available on request
Storage and insurance of customer-owned dies
Available on request
Shift pattern
Available on request

Alloys

Metals
Aluminium and zinc
Feedstock form
Ingot from established suppliers
Aluminium supplier
Metallco, Toten, Norway — secondary aluminium realloyed against international standards
Aluminium melting point
660 °C °C
Aluminium casting temperature
680–700 °C °C
Alloy selection
Made together with the customer, as part of the design review
Aluminium alloys, pressure die casting
Available on request
Aluminium alloys, gravity
Available on request
Zinc alloys
Available on request
Customer-specified alloy
Available on request
Material certificate
Available on request
Melt and batch traceability
Available on request
Recycled content
Available on request

Questions and answers

Heat treatment — common questions

That depends on the alloy and the temper, not on us. For the classic heat-treatable gravity alloy EN AC-42100 (AlSi7Mg0.3), EN 1706 states a minimum tensile strength of 170 MPa as cast and at least 290 MPa in the T6 condition — and the yield strength more than doubles, from 90 to 210 MPa. Those are standard values from the alloy standard, not measurements on our parts.

Available on request.

It can. Solution treatment happens close to the melting range of the alloy, and thin or asymmetric sections can pull. If a part is both heat treated and has tight tolerances, we normally put the machining after the heat treatment — not before.

Unsure whether your part meets its strength requirement?

State the requirement in your enquiry and we will tell you which combination of process, alloy and heat treatment meets it.

Send an enquiry

Henger sammen med

Zinc die casting

Thinner walls, sharper detail, longer die life — and almost no Norwegian suppliers.

Aluminium die casting

Thin walls, complex geometry and seconds per shot — in recycled aluminium.

Gravity die casting

Lower tooling cost, smaller series — and the only route to heat treated strength.

Send tegningen — få en støpbarhetsgjennomgang

Vi ser på godstykkelse, slipp, radier og delelinje før vi gir pris. Svar innen 24 timer på virkedager.

Send tegning

Vi bruker anonym besøksstatistikk for å forbedre nettstedet. Google Analytics lastes kun hvis du samtykker. Les mer