Ultem is a high-performance plastic with excellent mechanical and chemical properties. It is a useful material for high-value industries such as aerospace, automotive, electronics handling and transportation. Machining is one of the most important manufacturing techniques for Ultem production.
This article is about Ultem CNC machining. We explain what Ultem is, the different qualities of Ultem, and Ultem's editing capabilities.
What is Ultem?
Let's start with a simple question: what exactly is Ultem? Polyetherimide (PEI brand: Ultem) is a plastic with a clear amber appearance and a wide range of desirable material properties.
It is one of the strongest and most resilient high-performance plastics in its family and can maintain its performance in extreme conditions. For comparison: it is quite similar to the popular thermoplastic PEEK (polyetherketone).
Ultem Material Properties
The diverse properties of the Ultem material reveal what makes it so superior and unique among thermoplastics, especially in terms of machinability.
Thermal stability
Ultem is a great material for high temperature applications. It has remarkable thermal stability, allowing it to maintain the material's properties at high temperatures above 200°C. Furthermore, it maintains its rigidity and resists deformation even at high temperatures.
Chemical resistance
One of Ultem's most attractive features is its excellent chemical resistance. It stands out among amorphous thermoplastics for being more resistant to chemical reactions with compounds such as acids, oils, fats, alcohol, etc.
Furthermore, it is also more resistant to stress cracking when in contact with various chemical compounds. This property is useful in Ultem CNC machining because most coolants/lubricants are aqueous solutions of such compounds.
Mechanical solidity
Ultem features a number of strong mechanical properties that make it very useful for high-strength applications. Firstly, it is a robust material with a tensile strength of 110 MPa. It also has high resistance to bending and impact.
Furthermore, it is a rigid thermoplastic. With an impressive Rockwell M hardness of 109, it is abrasion and surface resistant.
Electrical insulation
Ultem is an excellent electrical insulator with high dielectric strength. This, combined with its unique appearance, offers great opportunities for electrical product designers. It is the ideal material for making adapters, terminals and casings for electrical circuits.
Dimensional stability
Ultem's dimensional stability is related to its mechanical and thermal properties. Due to their high rigidity and hardness, products manufactured by Ultem machining are very precise. Furthermore, the high thermal stability not only prevents excessive deformation during machining, but also guarantees dimensional stability at high temperatures.
Low flammability
Ultem also features incredible flame resistance. Meets UL94 V-0 specification for flammability. Additionally, it produces very small amounts of non-toxic smoke.
These are excellent properties for high temperature maintenance, especially in Ultem machining where high temperatures tend to occur.
Different Ultem qualities
Ultem is a versatile material with several grades, each offering a different combination of properties. In this section we will discuss the common Ultem notes.
Ultem 1000
Ultem 1000 is the most famous Ultem strain. It offers all of the above mechanical and chemical properties and has the classic transparent amber tone. However, it is also available in other colors on the market. There are also opaque variants.
Additionally, it is an economical machining thermoplastic that offers high temperature processability and flame retardancy.
Additionally, Ultem 1000 is a very versatile material used in electronics enclosures, light and medium duty automotive and aircraft interior components, household appliances and in food production.
Ultem 2100
Ultem 2100 is a 10% fiberglass filled variant of the standard Ultem material. The addition of glass fibers improves its mechanical strength and stiffness, which is a good improvement for high-intensity applications. Its chemical properties and overall machinability are also comparable to other standard Ultem types.
Due to its rigidity and chemical resistance, Ultem is the perfect material for rigid packaging, automotive replacement parts and electronic material handling.
Ultem 2300
Ultem 2300 is the best known of the fiberglass reinforced Ultem grades. With a glass fiber content of 30%, it has incredible strength, rigidity and dimensional stability, as well as high thermal stability.
For this reason, it is often the first choice for designers who want to take advantage of Ultem's superior chemical properties but require additional improvements in mechanical properties.
Ultem 4000
Ultem 4000 is a high performance Ultem grade with fiberglass, PTFE and graphite powder fillers. These additional compounds significantly improve wear resistance by reducing the coefficient of friction. They act as an internal lubricant.
Its main applications include cases for electronic devices, personal accessories and, due to its soft and wear-resistant properties, in the beverage industry.
Challenges and tips for editing Ultem
Ultem is highly machinable and therefore not as difficult to work with as metals. However, it is not very easy to machine due to specific machining problems such as thermal softening and stress cracking. Therefore, machinists have put together some tips for the challenges they face when machining Ultem.
Annealing to Relieve Stress
Annealing is a heat treatment process in which material is held at a specific temperature for a specific time to relieve internal stresses. It is a pre-editing process that greatly improves final machinability.
Due to its amorphous nature, it is susceptible to stress cracking during machining, which is by far the most common challenge in Ultem CNC machining. With a balanced annealing cycle, the risk of cracking can be reduced to a manageable level.
Coolant to prevent cracking
Thermal stability is an important feature of Ultem, but risky applications still require the use of coolant/lubricant. Additionally, fiberglass reinforced variants such as Ultem 2100 and Ultem 2300 have slightly lower thermal stability than standard Ultem grades, so coolant is recommended.
Depending on the work process, machinists can choose between mist and flood cooling. For example, during drilling, an ample supply of coolant is needed to prevent cracking.
Sharp and hard cutting tools
One of the factors that negatively affect the machinability of Ultem is its wear resistance. If the tool geometry and material are not optimized, the cutting edge of the tools will become dull.
From a materials perspective, high speed steel (HSS) is a good enough material for standard Ultem like Ultem 1000. However, for fiberglass reinforced variants like Ultem 2300, harder CNC cutting tools like hard metal may be more suitable.
Chip management
Ultem produces long, fibrous chips. This can be problematic if there are not adequate chip management measures in place. Typically, occasional soda or vacuum suction is the solution.
Moderate cutting parameters
Although Ultem is highly machinable, it is sensitive to aggressive cutting. The main reasons for this are its slight fragility and the risk of cracking. High feeds and speeds can cause fractures/cracks and high heat input.
Therefore, it is advisable to be somewhat conservative and take time to optimize cutting parameters to avoid quality issues.
Surface Finish Options for Ultem Machined Parts
There are various surface treatment options for Ultem CNC machining parts because it has high dimensional stability. Combined with a smooth surface, it becomes a viable and lightweight replacement for low-strength metal parts. The main surface finishing options include:
Processed
With Ultem CNC machining, very thin surfaces of up to ± 1 µm can be obtained. For most applications this is more than sufficient and the part does not require finishing operations other than sanding/filing.
pearl rays
The most common and standard surface treatment for Ultem machined parts is shot blasting. Machinists can achieve fine surface finishes using automated operations. With the different grain sizes of the abrasives, the final result is quite good for medium roughness parts.
Falling down
Tumbling involves placing the Ultem part in a rotating vibrating chamber along with other materials, such as ceramic particles. The machine “rotates” the part for a while, the particles smoothing the surface by flattening the protrusions. Ultem parts generally use harder materials, such as ceramic, due to their high hardness.
PEEK vs. PEEK machining Ultem: What are the differences?
Ultem and PEEK have very similar material properties. Therefore, they are also similar in terms of machinability. Perhaps the biggest difference between them is the price: PEEK is significantly more expensive than Ultem.
In general, PEEK is slightly better than Ultem in terms of tensile strength, impact resistance, and high temperature resistance. Therefore, PEEK processing is a little more difficult and energy-intensive than Ultem processing. Its higher friction and wear properties lead to greater tool wear and higher cutting temperatures.
Consequently, these two materials are still very similar in terms of machinability. The same precautions are taken for both: annealing, selecting tools with sharp edges, and cooling. However, PEEK is a bit tougher and often requires more care.
For example, HSS tools are suitable for low-strength Ultem like Ultem 1000, but for PEEK, experts always recommend using carbide or even diamond tools. Likewise, PEEK requires better cooling in all cases, while Ultem can be processed without flood cooling.
Ultem Machined Parts Applications
Ultem CNC machining is used in many industries, from precision aviation to home appliances. Some of the most important application areas are:
- Semiconductor equipment
- Washers, gaskets
- Medical equipment
- Electronic connectors and housings
- Aircraft interior components
Do you need CNC machined Ultem parts?
Concluding
Ultem is a high-performance thermoplastic with several beneficial properties, including high strength, thermal and chemical stability, and most importantly, machinability. Thanks to Ultem's numerous qualities, it is the perfect choice for a wide range of industrial and commercial applications.
Common questions
Is Ultem editable?
As long as tools with very sharp edges, adequate cooling and low to medium parameters are used, Ultem is an easy-to-machine material that does not pose major challenges.
How does Ultem compare to PEEK?
Ultem and PEEK are comparable materials. While PEEK is slightly stronger and more durable, Ultem is more economical without having to make major compromises in material properties. Ultem is also easier to process than PEEK.
What are the benefits of Ultem?
Ultem has numerous advantageous material properties. These include high strength, impact resistance and hardness. Furthermore, it is thermally and chemically stable and maintains the properties and shape of the material at high temperatures and when in contact with compounds such as acids, alcohols, fats and oils.
