Zamak Die Casting: The Ultimate FAQ Guide

I know you are probably looking for more information about Zamak die casting.

A reason this guide explores everything you need to know about die casting these alloys.

So, before starting this die casting process, read this guide.

What Are the Benefits of die

Here are some of the benefits of zamak alloys;

Zamak alloys produces a precise and resilient casting with high fluidity when it is molten.

They are tough and have great rigidity than aluminium counterparts.

Die casting zamak alloys are stronger hence they can be produced with thinner walls and less material to optimize strength compared to other materials like plastics and aluminium.

Another advantage is that zamak alloys has a lower melting temperature hence it can last 20 times longer than aluminium alloy.

die casting zamak alloy

die casting zamak alloy

When using zamak alloys, they provide a decorative and a great adhesion of any finish to its substrate thus these finishes are corrosion resistance.

Zamak alloys also allows surfaces to act as brushings for structures in motion since they have good waring and bearing properties.

They are also 100% recyclable hence all the by-products of the casting process can be remelted and cast again without degradation.

Its fluidity provides increased precision hence allowing designs that do not require additional expensive machining.

They are cost effective since they solidify rapidly in lower melting temperature thus producing more parts in the same amount of time.

Are There Limitations of Die Casting Zamak Alloys?

These are the limitations of zamak alloys;

  • If the temperature is too low, the properties of alloy components fall remarkably.
  • The alloy becomes less ductile when mixed with other metals like tin or lead hence it compromises its corrosion resistance.
  • It is unsuitable for lightweight application since it yields much weight compared to other non-ferrous alloys.
  • They become more fragile if the temperature is too high thus the components tensile strength decreases.

Which Components and Parts Will You Make from Zamak Die Casting?

Zamak die casting is a base zinc metal alloyed with magnesium, copper and aluminium elements.

The name zamak is from the metals which the alloys are composed of.

The parts produced by zamak alloys are;

  • Wheel spacers.
  • Command cable terminals.
  • Engine blocks.
  • Alternator housings.

How Does Zamak Die Casting Compare To Aluminium Die Casting?

  • Zamak die casting has a low melting temperature hence quicker to manufacture compared to aluminium which has ahigh melting temperature.

zamak die casting

zamak die casting

  • Aluminium alloy is a lightweight while zamak alloy is heavier thus energy efficient and has lower production cost hence is good where weight is less important.
  • In casting zamak strength is higher than aluminium alloy hence the precision is significantly good and the wall thickness can be reduced.
  • Zamak alloy lifetime is more durable compared to aluminium alloy which have a maximum life time of 100000 shots.

Aluminum alloy

 aluminum alloy

Are Zamak Die Cast Parts Durable?

Absolutely yes.

The parts provide a greater impact of resistance to shocks, wear and corrosion compared to other alloys hence they are versatile in finishing the articles.

Its ductility and good strength allow to have flexibility in the design of small parts and details.

Do Zamak Die Cast Parts Require Heat Treatment?

Yes.

The parts are melted at the temperature of about 420c adjacent to the die casting machine hence the alloy is injected into a mould.

Zamak alloys to obtain pieces with very low tolerance limits due to its low melting point and high fluidity.

Heat treatment is very important hence to improve the hardness, toughness, ductility, strength and corrosion resistance of the alloy.

We can use annealing, case hardening, precipitation strengthening, tempering, carburizing and normalizing heat treatment techniques.

How Can You Increase Efficiency Zamak Die Casting Process?

In the casting process, one has to be with the complete knowledge of the entire process developed inside the casting machine from the melting pot to the die.

This will help to obtain date and improve the filling parameters, machine parts and moulds.

The work starts by characterizing the flow happening inside the mould at the moment of cavity fill by analysing computer fluids dynamics simulations.

Quantify the porosities detected on the cut terminal surface hence ultimate goal is achieved with the modification of molten metal flow systems such as channels and sprues.

Which Zamak Die Casting Defects Are Common?

Zamak die casting alloy has many sources to cast defects hence here are some of the common defects, causes and their remedies;

  • Cracks appears when a metal does not have sufficient strength to resist tensile force during solidification.
    To avoid cracks, set die coat spray properly in proper mixture hence maintain die temperature within limit by setting die open time.
  • With high die temperature, a thin film of small surface blows up on the surface of the component.
    Proper flow of die coat spray is usually maintained to prevent blisters hence proper mixture of die coat chemical is done.
  • Blow holes.
    This occurs when there is no proper venting hence the metal can’t hold as much gas as the fluid form.
    It is prevented by proper venting thus set spray for adequate amount of die coat.

How Can You Reduce Defects During Zamak Die Casting Process?

Maintain die temperature within limit by setting die open time, die open and close speed properly.

Check and maintain injection pressure and maintain oil pressure.

Provide proper venting.

Check and maintain continuous cycle time and die opening time.

Check and open choked die cooling.

Which Temperature Is Suitable for Zamak Die Casting?

The parts are melted at the temperature of about 380-420c adjacent to the die casting machine hence the alloy is injected into a mould.

When the melting temperature is too low, the flow property will be poor hence it will affect the surface quality of the zamak die casting.

When the temperature is high, the casting crystallization is good and mechanical performance is reduced.

What Is the Chemical Composition for Zamak Alloy for Die Casting?

Zamak die casting is a base zinc metal alloyed with magnesium, copper and aluminium elements.

The name zamak is from the metals which the alloys are composed of.

zamak alloy

zamak alloy

They are distinguished from other zinc aluminium alloy because of their 5% composition of aluminium.

Which Types Of Zamak Alloys Are Suitable For Die Casting?

Here are most common zamak alloy;

Zamak 2

It has a great strength compared to other alloys due to 3% copper increase in it hence making it expensive than others.

Has the same composition as zamak 3 hence composed of magnesium, copper, zinc and aluminium.

zamak 2

zamak 2

It is used for die casting hence it is also known as Kirk site.

Also used for mandrels for metal spinning.

Zamak 3

It is the most used zamak alloy compared to other alloys.

Composed of 90% zinc ,10% aluminium.

Mostly preferred for die casting.

zamak 3

zamak 3

Zamak 4

It helps in ductility of zamak 3 hence it reduces the effects of die soldering.

zamak 4zamak 4

Zamak 5

It also has same composition as zamak 3 but has addition of 2% copper hence to increase its strength corrosive resistance and hardness.

 zamak 5

zamak 5

Zamak 7

It is used in casting thin wall hence has less magnesium to increase ductility and fluidity.

Nickle is added to it to reduce inter-granular corrosion and more impurities are also controlled.

zamak 7

zamak 7

Which Quality Standards Should Zamak Alloy for Die Casting Conform To?

The quality standards of zamak alloy is defined by country hence it can be called by different names based on standards.

COUNTRYZINC CASTINGZINC INGOT
AustraliaAS 1881-

SAA H64

AS 1881-

SAA H63

CanadaCSA HZ11CSA HZ3
USASTN B86ASTM B240
EuropeEN12844EN1774
China       –GB 8738-88
JapanJIS H5301JIS H2201
International               –ISO 301

Which Critical Facts Should You Consider Before Zamak Die Casting?

The following are factors to consider before die casting;

  • Cast surface finish.
    Roughness of the cast surface in some casting is critical to successful use hence cast components do not have standard surface finish specifications.
  • Order quantity.
    This is more important in selecting correct tooling hence each production order requires separate processing.
  • Technical services.
    An additional amount of service or technical assistance will be required from metal casting due to more complex engineered cast components.
  • Value-added operations.
    Heat treating, painting and inspection are some of the additional operations that can efficiently performed by a metal casting facility.
  • Geometric complexity.
    Casting design complexity and application has a great impact on cost hence processes utilized for tight dimensional tolerance and casting tend to be costly.
  • Dimensional allowance and tolerances.
    Tolerance and allowance are the major factors the buyers and the designers must have hence more tolerance increases the cost and lengthen delivery time.
    Less tolerance leads to extensive machining and a heavier section size than required.
  • Quality requirements and assurance.
    Good quality begins with good design for performance and manufacturability hence high unnecessarily quality requirements increase the total costs.
  • Well packaging side by side is considered compared to bulky packaging which damages the casting on arrival.
  • Lead times, first article delivery.
    This is defined as the amount of time between contract agreement and delivery of the first article.
    Lead time is reduced with metal casting compared to other manufacturing methods by shortening the time required for finishing and machining.
  • Type of metal.Different compositions have different levels of castability, weldability and fluidity.

What Does High Pressure Die Casting Zamak Process Involve?

High pressure die casting involves;

  • Preparing the mould.
    At this stage the lubricant is applied to the interior walls of the mould hence to regulate the moulds temperature and for easier removal of casting.
  • After preparing the mould, the molten metal is then injected in it when the mould is tightly sealed and closed.
    The mould has to maintain the pressure until molten metal has cooled and solidified.
  • Cavity injection.The new cavity from the mould is then ejected by the manufacturing company using automatic ejector pin.
    This process cannot be accomplished if the cavity is still liquid hence it has to be solid for it to eject.
  • At this final stage, any excess scrap metal is separated from the new cavity before the mould can be reused.

 Are There Benefits of High Pressure Die Casting of Zamak?

The benefits include;

The moulds are durable hence more parts can’t be manufactured to decrease the number of components requested.

The fusion has a good surface finish thus reducing the thickness of the plate walls hence reducing the overall weight of the fusion.

zamak high pressure die casting

zamak high pressure die casting

It has a higher production speed when compared to the flow pouring under the effect of gravity.

High pressure has the ability to produce flows of specific dimensions hence to re3duce processing operations.

Is Zamak Alloy Suitable For Hot Chamber Die Casting?

Absolutely yes.

The hot chamber system is used with metals such as; magnesium, lead and zinc.

The furnace on the machine is attached by a metal feed system called gooseneck where the injection process of a hot chamber is thrust in the molten metal.

Then molten metal is then allowed to fill the cylinder by closing the die and piston rising to open the port.

The molten metal is then pushed through the gooseneck and nozzle into the die cavity when the plunger seals the port hence it is held under pressure until it solidifies.

When the die open, the molten metal flows back through the nozzle and the gooseneck hence the casting remains in the ejector side.

Then ejector pin pushes the casting out of the ejector die thus the molten metal flows through the inlet to refill the gooseneck.

Is Cold Chamber Die Casting Suitable For Zamak Alloys?

This is used for metals that have high melting point such as; copper, zinc alloys, brass and aluminium alloys.

The molten metal is ladled into the cold chamber shot sleeve and the die closes.

The plunger then pushes the molten metal into the die cavity where it is held under pressure until it solidifies.

The casting remains in the ejector die while the die opens and plunger advances hence the ejector pin push the casting out of the ejector half of the die.

Is Gravity Die Casting Best Choice For Zamak Die Casting?

Yes.

Here is step by step process of gravity die casting;

  • Prepare the die by heating it up to a preferred temperature and spray it with a refractory coating.
    The refractory helps to maintain the temperature of the die during the manufacturing process.
    It also prevents premature solidification when the cast is once set.
    When using high pressure, the die is usually closed and clamped tightly together.
  • After the preparation, no forces or pressure is used hence the molten metal is taken manually or with automated ladle from furnace into the die.
    Due to the natural gravity, the molten liquid makes its own way down into the cast when inserted into the die in a vertical position.
    Turbulence is reduced to prevent porosity and avoid high pressure thus production of smoother components and parts.
  • This is done to prevent irreversible defects hence the cast is given enough time to cool and solidify taking the shape of the mould.
    The cast is left to set completely before the die is unclamped.
  • The ejector pins are used to remove the cast parts carefully out of the gravity die casting machine hence when the die halves are unclamped and opened.
  • Excess materials such as runners, gate, sprue and flash are removed from the casting using variety of tool hence to take away sharp edges too.
    The parts are then cleaned after creating the desired component shape before despatch to the buyers.
    This is the last step of gravity die casting.

What Determines the Cost Of Zamak Die Casting Process?

Factors that determine the cost of zamak die casting process are;

  • Mould cost.
  • Material cost
  • Production cost.

                                Mould Cost

It is very effective since the optimization of mould design and reuse of existing mould is used thus reducing the cost of die casting.

                                 Material Cost

This depends on the material required and the unit piece of the material.

The use of the thinner walls will lower the cost of the material since it requires a larger channel system to ensure that the entire part fills quickly.

                                  Production Cost

The cost Is calculated on an hourly rate hence the hourly rate is proportional to the size of the die casting machine.

However, the type and the size of the machine affects the cost of the die casting process.

How Do You Test Quality Of Zamak Die Cast Components?

  • Salt spray testing.

This procedure is usually conducted in accord with ASTM B117.

The procedure has many challenges but some consider it for coatings.

  • Destructive test.
    This test is used to detect the porosity during the casting period hence the porosity can weaken the integrity of the final part.
  • Visual test.
    This is established by the customer by looking hence a piece of zamak may not look right visually thus it may require retooling.
  • Leak test.
    This is done using an air decay leak tester hence to detect if the casting is leaking due to porosity and worn-out dies.
  • Poke yoke method.
    The method is used to detect poor trimming process by leaving excess material on your part.
    The procedure helps you prevent poor die cast maintenance and poor design.

How Do You Choose Suitable ZAMAK For Die Casting?

A good zinc alloy is one which has good heat conduction, good vibration damping characteristics and an excellent electromagnetic shielding performance.

It should have high purity hence low impunity content of zinc ingot is based on high purity of zinc materials.

Has a low melting point hence the temperature can be controlled below 420c and it must also have less zinc slag which are produced during melting.

Knock off to see the section hence if the zinc section is fine then the alloy is generally better.

Stainless steel spoon should be used to contact liquid alloy hence when if it solidifies it becomes hard thus a better zamak for casting.

If the alloy has a high ductility, it means that it is good for die casting process hence producing a product that expands without fracturing under pressure.

Other factors to consider when choosing suitable zamak for die casting are;

  • Raw material cost.
  • Size of the finished part.
  • Thermal conductivity.
  • Recyclability
  • Corrosion resistance.
  • Finish needs and option.

Is It Possible to Handle Zamak Die Casting Process with Precision?

Of course, yes.

The high precision of the zamak die casting simplifies the process of varnishing, painting, polishing and plating.

The good strength and its ductility enable a great flexibility in the design of small parts and details compared to other alloys.

How Long Will Moulds for Zamak Die Casting Last?

Zamak die casting mould usually last over two million of cycles thus ten times higher than aluminium die casting.

The mould i8s used to obtain items by adding removable and replaceable inserts thus building a new mould would not be economical.

Is There Minimum Wall Thickness for Zamak Die Casting?

Definitely yes.

Wall sections are always thinner hence to ensure there is resistance and stiffness.

This increases the production speed by minimizing the required weight of metal and accelerate solidification into mould.

Which Surface Coating Can You Apply On Zamak Die Cast Parts?

Surface coating is done to increase the mechanical, electrochemical and thermal performance of the material.

The following are some of surface coating that are used to apply on zamak die casting parts;

  • Polyester powder coatings.

Dry electrostatic process is used during this coating as powder hence solvents are not used to prevent the formation of solvent caused defects.

  • Sprayed coatings

It involves different chemistries like polyester, phenolic and epoxies.

  • Zinc black.

This process helps in corrosive environment hence a thick black phosphate is conferred to the casting.

  • Copper-tin-zinc electroplate.

The coating turns the finish to black though it gives zinc a correct protection thus it is dull and silvery on the zinc surface.

  • Galvanize coating.

This coating help to protect the metal from corrosion and improves the appearance of the surface.

The desired appearance is achieved only by selecting chromium [111] containing passivation such as black passivation, thin film passivation and thick film passivation.

For any questions or inquiry on Zamak die casting, contact us now.

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