Ultem 1000 – CNC Machining

Ultem 1000 is used for CNC machined components that must hold geometry at elevated temperature while maintaining electrical and mechanical stability.

Its machining behavior is heat-sensitive, with a tendency to soften locally and form stringy chips if tool edges are not sharp and chip evacuation is weak.

At ShvaveyMetal, Ultem 1000 CNC machining strategies are defined around thermal control, rigid workholding, and finishing passes that protect edge definition and tolerance integrity.

Ultem 1000 is an unfilled PEI (polyetherimide) thermoplastic selected when high-temperature capability and dimensional stability are required in machinable polymer parts.

Mechanical Properties (Typical)

Property Typical Value Units
Density ~1.27 g/cm³
Tensile Strength ~105–115 MPa
Yield Strength ~95–105 MPa
Elongation at Break ~40–70 %
Elastic Modulus ~3.1–3.4 GPa
Hardness ~110–120 Rockwell M

Mechanical properties depend on grade, moisture state, and whether the stock is extruded or molded.

Thermal & Physical Properties

Property Typical Value Units
Glass Transition Temperature (Tg) ~217 °C
Continuous Service Temperature ~170 °C
Thermal Conductivity ~0.22 W/m·K
Coefficient of Thermal Expansion ~50–60 µm/m·K

These properties drive toolpath planning and inspection strategy when tight tolerances are required at temperature.

Chemical Resistance (General)

Substance Category Resistance Level
Water / Aqueous Solutions Good to Excellent
Oils and Greases Good
Alcohols Good
Dilute Acids Good
Strong Acids / Alkalis (Hot) Fair to Poor
Aromatic / Halogenated Solvents Poor

Chemical performance depends on temperature, exposure duration, and stress level in the machined component.

Ultem 1000 machining behavior is governed by heat management, chip control, and surface integrity sensitivity in thin features.

Key machining characteristics include:

  • Stringy chip formation requiring reliable chip evacuation and conservative engagement
  • Risk of edge smearing or local softening if surface speed is excessive
  • Good finish potential with sharp tools and stable feeds that avoid rubbing
  • Sensitivity to dwell marks during finishing passes, especially on visible surfaces
  • Dimensional stability is strong for a polymer, but thermal expansion must be accounted for in tolerance planning

Machining is typically performed with air blast or a controlled coolant strategy, using sharp carbide tooling and parameters that maintain continuous cutting without dwelling.

Benefit Description
High Temperature Capability Maintains performance where many plastics soften or creep
Dimensional Stability Supports tight tolerances relative to common engineering plastics
Electrical Insulation Properties Suitable for electronic and high-voltage assemblies
Flame Performance (Grade-Dependent) Supports applications with fire behavior requirements when specified
Good Strength-to-Thickness Use Performs well in thin-wall housings and structural polymer components

Ultem 1000 is commonly used for CNC machined components such as:

  • High-temperature electrical insulators and connectors
  • Semiconductor and test equipment components requiring thermal stability
  • Medical device components requiring repeated thermal exposure
  • Fixtures and tooling elements used near heat sources

Application suitability depends on service temperature, dimensional stability targets, and chemical exposure.

Variant / Form General Characteristics
Ultem 1000 (Unfilled PEI) Baseline grade; best combination of machinability and toughness
Reinforced PEI (Glass-Filled) Higher stiffness and lower CTE; increased tool wear and different chip behavior
Flame-Retardant Grades Specified where fire performance is required
Extruded vs Molded Stock Differences in residual stress and stability can affect precision features

Machining parameters and stability planning can vary between unfilled and reinforced PEI, even when geometry is similar.

  • Account for polymer thermal expansion in stack-ups and mating fits
  • Avoid thin unsupported walls that can deflect under cutting load and heat
  • Define surface finish requirements early, especially for sealing and interface faces
  • Minimize sharp internal corners where stress concentration can initiate cracking under load
  • Plan chip evacuation paths for deep pockets and small bores to prevent heat buildup

Process stability improves when tolerances, inspection temperature, and service temperature are aligned from the start.

FAQ

What is the machinability of Ultem 1000?

Ultem 1000 machines cleanly with sharp tooling and produces good surface finishes, but it is notch-sensitive and prone to stress cracking. Sharp carbide tooling, moderate speeds, light finishing passes and avoidance of sharp internal corners are important. Coolant compatibility must be verified, as some fluids initiate crazing in PEI.

Why does Ultem crack or craze during or after machining?

PEI is susceptible to environmental stress cracking: residual machining stress combined with contact with an incompatible coolant, solvent or cleaning agent initiates crazing, sometimes days later. Prevention means verifying fluid compatibility, minimising residual stress through controlled cutting, and annealing critical parts to relieve stress before service.

What tolerances can be held on machined Ultem 1000 parts?

Ultem holds tolerances well for a thermoplastic, benefiting from high stiffness and relatively low thermal expansion compared with materials such as Delrin or nylon. Tight tolerances remain achievable with controlled parameters, stress management and inspection under stable conditions. Glass-filled Ultem 2200 offers even greater dimensional stability.

What are machined Ultem 1000 components used for?

Applications include sterilisable medical devices and instrument components, electrical insulators and connectors, semiconductor handling fixtures, and fluid handling components. It is chosen where a part must withstand heat and repeated sterilisation while holding tight tolerances and electrical performance.

Should Ultem 1000 be annealed after machining?

For critical or tight tolerance components, yes. Annealing relieves residual stress introduced during machining, reducing the risk of later stress cracking and improving dimensional stability. It is particularly recommended where parts will be exposed to solvents, cleaning agents or repeated sterilisation cycles.


Why Machine Ultem 1000 at ShvaveyMetal

ShvaveyMetal machines Ultem 1000 using CNC workflows focused on thermal control, sharp-tool finishing, and condition-aware inspection for tight tolerance polymer parts.

This approach supports repeatable geometry and surface integrity for high-temperature applications where Ultem 1000 material properties are part of the functional requirement.