Investment Casting

Dean Group / Services / Investment Casting

Investment Casting Capabilities

A specialist investment casting firm, with over five decades of experience in manufacturing precision investment castings for demanding industries.

From ferrous to non-ferrous metals and to other exotic metals, we can design and volume manufacture investment castings to a wide range of design specifications.

We have a fully equipped foundry based in Manchester that manufactures excellent made-in-UK castings. We also have reliable international supply chain sourcing operations in China and India coupled with UK stock holding facilities to overcome extended lead times from overseas, enhancing our manufacturing capabilities.

Dean Group International offers a variety of investment casting techniques from our UK-based foundry in Manchester.
We create castings designed to meet your specific requirements and the high standards of your industry. Our investment casting manufacturing capabilities include:
Premium Grade Investment Casting

Commercial Grade Investment Casting Service

We also offer a commercial grade investment casting service, which offers design flexibility and good cast integrity. This process is ideal for larger and less intricate designs with capabilities to cast parts up to 100kgs. It is also best suited for medium to large-volume runs with virtually no tool wear and overall reduced production costs.
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Premium Grade Investment Casting

Premium Grade Investment Casting Service

Our premium grade investment casting is suitable for several applications, including the manufacturing of complicated shapes that can’t be produced with other methods. This method can cast individual parts up to 30kgs with 1000 x 620 x 380 (mm) dimensions. It is highly accurate and consistent, perfect for both low and high-volume production.
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Elite Aluminium Casting

Elite Grade Investment
Casting Service

The aluminium investment casting (ELITE) process allows for a range of part sizes and weights to be cast with excellent mechanical properties. It also produces parts with an enhanced microstructure that are gas-tight, and there is also no need for ‘HIP’.
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At Dean Group International, we have been providing specialised metalworking services, including lost wax casting, since 1972. We pride ourselves on being able to tackle technically challenging projects and will supply you with the parts you need. We only use the highest quality materials , and we inspect every product we manufacture.

We are happy to discuss your requirements, designs, and capabilities, help advise you on the best manufacturing process for your needs, or just tell you more about our metal casting foundry.

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Investment Casting Process

Investment castings, also known as lost wax castings, are formed by a traditional process, which has been used for centuries to produce detailed, intricate metal parts and components. Compared to other manufacturing methods, it is a cost-effective way of producing intricate products, providing significant design flexibility, with excellent dimensional accuracy and surface finish.

The investment casting process uses a detailed wax pattern produced from a master tool, which is then coated with a layer of refractory ceramic slurry to create a solid shell. The wax pattern is melted out, and the molten metal is poured into the shell. Once the metal has cooled and set, the shell is removed, and the part can be finished and quality-checked.

3D printing can be used to rapidly prototype the initial wax pattern, which can then be used for testing and validation before moving on to full-scale production.

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3D Printed Wax
A wax pattern needs to be created in order to form the end-cast product. Usually, this is done with tooling or dies, but in this case, we can negate the need for tooling and 3D printing directly into wax from a 3D model. This process allows for quick and accurate prototype product manufacture for trial testing and review.
Wax Assembly
Once the wax patterns have been created, either from prototype 3D printing or tooling for casting, we would then need to assemble them into something commonly known as a ‘tree’. This tree comprises multiple wax patterns attached to its exterior. The more wax patterns you can attach to the exterior, the more efficient a tree is. You would get many wax patterns on one tree if they were small; you would only get a few if they were larger.
Investment
Investment Casting got its name from this stage of the process; this is the process where you investment in material to form a shell. We form this shell by submersing the now assembled tree into a specially designed slurry mixture. This slurry mixture is a semi-viscous adhesive, which we then cover in a special sand. Then, left to dry, the process is repeated a number of times to build up a thick shell that is permeable to air but can withstand immense temperatures and hold molten metal.
Wax Removal
The wax tree is now fully encased in a thick and durable shell. The wax has now done its job and needs to be removed to reveal a hollow cavity. To do this, we need to go through a special process of heat and pressure. We load several trees into something called a Boilerclave. This piece of kit applies the required heat and pressure to cause the wax inside the trees to melt and exit out of the shell, leaving behind a hollow negative impression, generally known as the mould.
Firing
Firing the trees does two things: it fully bakes the shell to meet the required toughness required to withstand handling and pouring. The second is to bring the temperature closer to the temperature of what the metal would be. Metal is poured into the shell at around 1600-1700°C. If this were to be done in a shell at room temperature, then something called ‘Thermal shock’ would happen, which would cause shell failure. By bringing the shell up to 1000°C, the issue of thermal shock is removed, and the products are in full form once cast.
Casting
Metal ingots are added into a furnace, melted and brought up to a castable temperature of around 1600-1700°C. The shell is removed from the oven and brought over to the waiting molten metal. The metal is poured into the shell, which fills the internal voids with molten metal. Once cast, it is put to the side to cool down and solidify.
Fettling
Once the tree has cooled down to room temperature, we need to remove the shell from the exterior. This is usually done by high-force impact or sometimes by water blasting. Once the shell has been removed, the fully formed metal casting will be revealed. At this point, they are still attached to the tree and need to be removed. They are removed from the tree with various saws and plasma cutters. Finally, they are ground back to a finished cast state as per customer requirements.
Finished Casting
Once fettled, castings can undergo multiple post-process treatments such as shot blasting to improve surface finish, heat treatment to improve mechanical strengths, machining to meet higher tolerances and much more. Castings are versatile items that can meet many customer requirements.

Advantages

Investment castings have several advantages over other formed parts from processes such as sand casting and lost foam casting.

Investment casting is ideally suited to smaller, more intricate designs and provides the precision necessary to incorporate logos, product IDs and numbers onto the surface.

Unlike sand casting, which requires breaking apart the mould to divest the pattern, the investment casting process results in a smoother surface with only a minor parting line. Investment casting generally does not need much secondary processing (polishing, trimming, etc.). Investment casting uses hard refractory ceramic, creating finished parts with much tighter tolerances than sand casting.
A summary of investment casting benefits can be seen below:

Investment casting is age old manufacturing method of making intricate metal products. Simply put it is turning a master wax model into its metal counterpart. We do this by injecting molten wax into a pattern/tool which forms the shape of the part we wish to make. This process is repeated until the desired number of products are created. These products are then assembled onto something called a ‘tree’. This tree is then dipped into a semi viscous slurry mixture which acts as an adhesive, we shower special sand particles over the tree which sticks to the tree. We leave this to dry and repeat the process up to 8-10 times to form a durable and heat resistant shell. The now encased wax needs to be melted out to leave a hollow cavity. This cavity will then be back filled with molten metal to form the metal parts. Once poured and cooled the shell is removed to expose the near net shape metal product. Parts are then cut from the tree and then post processed to the customers desired specification.

Investment casting can be traced back to around 5000 years ago. The earliest findings were found in Indus Valley Civilisation, Mesopotamia, height of the Egyptian & Chinese empires. Investment casting was a lot more rudimental in these times, mainly used to make basic copper figures, daggers, arrow heads and other such items. It was mainly low melting alloys in these times as that’s all that were available at the time.

The name investment casting is one of two common names for this process, also known as the Lost Wax Process. The name ‘Investment Casting’ comes from the shelling process where we ‘invest’ this refectory shell/sand media onto the surface. Because of this the name Investment Casting was taken for the process. The alternative process which it is know for ‘Lost Wax Process’ comes from the fact that each wax pattern we manufacture is a 1 of 1 single use pattern. So the wax pattern needs to be destroyed to proceed in the process so it is ‘lost’. Which drafted the name ‘Lost Wax Process’. Common misconception that the wax is thrown away which isn’t the case as the wax has a 99% reusable rate assuming it is processed properly.

The investment casting process can be technically used for any material in which can be melted and poured into a shape, the most common engineering alloys in which Dean Group can offer are as follows:

Dean Group is not limited to these alloys and can offer more depending on your requirements.

There are many manufacturing methods in the world to form metal products. Investment casting is usually called upon to form the cost intricate and detailed products in which other processes cannot form. This casting process is the most accurate at basic cast state then any other process which makes it perfect for the following industries:

  • Military/Defence
  • Aerospace
  • Nuclear
  • Automotive
  • Renewables
  • Mobility
  • General Engineering

Its precision makes it a cost effective solution to avoid expensive post processing.

There are many benefits to the investment casting process, a few highlight benefits:

  • Precision – The investment casting process has the highest tolerances achievable from any casting process within the cast state. This reduces the cost of post processing and reduces lead times to finished product.
  • Surface Finish – The cast finish on investment castings can achieve up to 3.2ra compared to their counterparts casting process such as sand casting which can achieve a range of 6.4-10ra. So a substantial difference in surface finish. Beneficial to costing & time saving as little to no post processing will be needed to improve the finish for most industries.
  • Complex Designs – With the precise nature of the process we can achieve extremely detailed design which other processes cannot. Products like impellers, one piece controller units with internal cavitations, complex pump bodies and much more.
  • Repeatable – Once a method has been generated to manufacture the item then the process can be repeated on a large scale producing consistent and reliable products.
  • Volume – The process is extremely diverse in its ability to offer 1 off is so required and 100,000 units. Normally most customers us the process for 00’s/000’s of items per time but the process is not limited to any number.
  • Timing – Once an efficient route is set up you could get products in the cast state in as little as 3-4 weeks.
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Other services available

Investment casting is a flexible process that offers competitive production costs against relatively low tooling outlay, in the full range of materials, and with low, medium, and high volume production capabilities. Due to the tooling construction and manufacturing process, there is a high level of design flexibility and dimensional accuracy. This results in lower post-cast process costs.

In addition to our investment casting, Dean Group International are able to offer a selection of other services, including die casting, pressure die casting, metal injection moulding, and forging. This allows us to provide the most appropriate metalworking process for your project’s needs.

We can help with the design process, from the initial concept to 3D CAD, casting simulation, prototype, and sampling to approved production. Alternatively, for existing parts, we can import existing CAD data to improve and manufacture your part.

Contact Dean Group International for Your Investment Casting Quote

To find out more about our investment casting, or to get a quote for your project, please get in touch with us on 0161 775 1633 or submit your enquiry online.
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