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HIPS thermoforming is widely used for trays, packaging inserts, appliance components, point-of-purchase displays and other products where manufacturers need a material that is easy to form, reasonably tough and cost-efficient.
HIPS stands for High Impact Polystyrene. It is a modified form of polystyrene designed to improve impact resistance while retaining the easy processing characteristics that make polystyrene attractive for thermoforming.
For many tray and packaging applications, HIPS does not need to provide the highest strength, transparency or heat resistance on the market. Its advantage is the balance it offers between:
Good thermoformability
Useful impact strength
Relatively low material cost
Easy cutting and fabrication
Good printability in suitable grades
Flexible surface finishes and colors
Suitability for high-volume production
This guide explains why HIPS plastic is widely used in thermoforming, its typical forming temperature, common applications and the limitations manufacturers should consider before choosing it.
HIPS is one of several commonly used thermoforming plastics. For a broader comparison of PET, PP, ABS, PETG and other materials, see our Thermoforming Materials Guide.
HIPS, or High Impact Polystyrene, is a rubber-modified polystyrene material.
Compared with general-purpose polystyrene, the modification improves toughness and impact resistance while keeping many of the processing advantages of polystyrene.
HIPS plastic sheet is commonly available in:
White
Black
Natural colors
Custom colors
Matte finishes
Smooth finishes
Gloss finishes
Textured surfaces
Different formulations can also be developed for thermoforming, printing and other fabrication processes.
This flexibility is one reason HIPS is used across packaging, displays, appliances and industrial applications.
HIPS is considered a relatively easy material to process by thermoforming.
Commercial thermoforming-grade HIPS sheets are specifically designed to provide good formability while maintaining useful impact strength and stiffness. Material suppliers also offer HIPS in different colors, gloss levels and surface textures.
For manufacturers, this translates into several practical advantages.
HIPS softens predictably when heated and can be formed into:
Shallow trays
Deep trays
Inserts
Packaging cavities
Covers
Liners
Display components
It can work with vacuum forming and other thermoforming processes depending on the product.
For deep cavities, manufacturers still need to control wall-thickness distribution through heating, mold geometry and, where necessary, plug assist or pre-stretching.
HIPS responds well to heating and cooling, which can be useful for high-volume tray production.
The exact cycle time depends on:
Sheet thickness
Heater output
Product depth
Mold temperature
Number of cavities
Cooling system
Cutting method
For packaging applications, these factors can be more important to production cost than a small difference in raw material price.
There is no single forming temperature that applies to every HIPS sheet.
However, Spartech's thermoforming data for High Impact Polystyrene lists a reference forming range of approximately:
330–350°F (166–177°C)
with an ideal forming temperature around:
340°F (approximately 171°C).
These numbers should be treated as a starting reference rather than universal machine settings.
Actual processing temperature depends on:
HIPS grade
Sheet thickness
Color
Surface finish
Heater configuration
Heating time
Product depth
Mold geometry
It is also important to distinguish between heater temperature and actual sheet temperature.
The heaters may operate much hotter than the plastic sheet itself.
In production, operators should monitor the sheet condition and forming result rather than relying only on the oven setting.
Possible results include:
Poor mold definition
Incomplete corners
Excessive forming stress
Uneven stretching
Possible results include:
Excessive sag
Local wall thinning
Webbing
Difficult sheet control
Surface deterioration
The material supplier's technical data should therefore be used as the starting point, followed by trials on the actual mold and thermoforming machine.
Trays are one of the applications where the advantages of HIPS become particularly clear.
A thermoformed tray normally requires:
Repeatable cavity geometry
Adequate stiffness
Reasonable impact resistance
Efficient cutting
Stable high-volume production
Competitive material cost
HIPS can meet these requirements without using a more expensive engineering plastic.
Typical products can include:
Product trays
Packaging inserts
Hardware trays
Cosmetic inserts
Electronic component packaging
Retail display trays
Appliance components
The exact sheet grade should always be selected according to the final product requirements.
For food, medical or other regulated applications, manufacturers must confirm that the specific HIPS grade meets the required regulatory and end-use standards. The fact that a material is HIPS does not automatically make every grade suitable for food or medical contact.
Cost is another major reason HIPS remains popular.
HIPS is generally positioned as an economical thermoplastic, and suppliers also offer utility grades specifically for applications where a lower-cost sheet with adequate mechanical performance is sufficient.
But packaging cost should not be evaluated based on price per kilogram alone.
The real cost of a thermoformed product can include:
Plastic sheet
Scrap percentage
Heating energy
Cycle time
Cavities per mold
Cutting
Labor
Reject rate
Recycling or regrinding of trim material
A material that forms reliably at high speed may reduce the total cost per finished tray even if another plastic has a slightly lower raw material price.
This is why HIPS is often attractive for large-volume applications where predictable processing matters.
Standard polystyrene is relatively stiff but can be brittle.
HIPS is modified to improve impact resistance.
Typical commercial HIPS data show useful impact performance while maintaining relatively high stiffness. Curbell, for example, lists typical HIPS at approximately 2.8 ft-lb/in notched Izod impact and a flexural modulus around 310,000 psi, although actual properties vary by grade.
For thermoformed packaging, this helps reduce the risk of cracking during:
Handling
Stacking
Shipping
Product loading
Final assembly
HIPS is therefore useful when standard PS would be too brittle but a high-performance engineering plastic would be unnecessary.
One useful advantage of HIPS is that suitable grades can offer excellent printability.
This makes the material attractive for:
Retail displays
Advertising panels
Signs
Branded packaging components
Printed inserts
Specialized HIPS print grades are available for:
Screen printing
Digital printing
UV digital printing
Offset printing
Spartech, for example, produces HIPS sheet formulated for ink adhesion and multiple printing processes.
However, printability depends on the actual sheet surface and grade.
Manufacturers planning to print after thermoforming should confirm:
Surface energy
Ink compatibility
Surface texture
Printing method
Whether printing occurs before or after forming
Printing before thermoforming can also cause graphics to stretch with the sheet, so artwork must be designed around the expected material movement.
HIPS is available with different surface appearances, making it useful when the formed product remains visible to the customer.
Options can include:
Matte
Smooth
Polished
Textured
Custom-colored surfaces
This can eliminate or reduce the need for secondary finishing.
However, thermoforming stretches both the material and its surface texture.
In areas with high draw, a texture may become less pronounced.
For visible products, engineers should therefore consider:
Which side faces the mold
Draw depth
Required gloss
Texture retention
Color consistency
before finalizing the sheet specification.
One important limitation of standard HIPS is poor UV resistance.
Spartech's FormPro HIPS rates the material's UV resistance as low.
Long-term sunlight exposure can contribute to:
Color change
Surface degradation
Reduced mechanical properties
Embrittlement
For this reason, ordinary HIPS is generally better suited to indoor products or applications where prolonged outdoor UV exposure is not expected.
If a thermoformed product will be used outdoors, manufacturers should evaluate:
UV-stabilized materials
Weatherable cap layers
Alternative plastics such as ASA
Outdoor coatings
rather than assuming standard HIPS will provide long-term weather resistance.
HIPS and standard polystyrene belong to the same material family, but their practical performance differs.
| Property | HIPS | General-Purpose PS |
|---|---|---|
| Impact resistance | Higher | Lower |
| Stiffness | Good | High |
| Thermoformability | Good | Good |
| Brittleness | Lower | Higher |
| Appearance options | Good | Good |
| Cost | Economical | Generally economical |
| Typical use | Trays, inserts, displays, appliance parts | Disposable products, rigid packaging |
The choice depends on whether the finished product needs the added toughness provided by HIPS.
HIPS should also not be treated as a replacement for every packaging plastic.
Opaque packaging is acceptable
Cost control is important
Good impact performance is needed
Easy thermoforming is a priority
Printing or colored sheet is required
High transparency is required
Product visibility is important
Clear retail packaging is needed
PET and PETG can provide much better optical clarity, while HIPS is typically used as an opaque sheet.
Material selection should therefore be based on the end product rather than simply choosing the material that is easiest to form.
Possible causes include:
High draw ratio
Uneven heating
Tight corners
Poor material distribution
Possible improvements include zoned heating, larger radii or plug assist for deeper cavities.
Webbing can occur when excess material gathers between cavities or mold features.
Check:
Mold spacing
Sheet temperature
Sheet sag
Mold geometry
Possible causes include:
Sheet too cold
Insufficient vacuum
Poor venting
If the sheet becomes difficult to control before forming, overheating or excessive heating time may be responsible.
Adjusting heater zones can often provide better control than simply reducing the overall heater temperature.
The machine should be selected according to the finished tray rather than the material name alone.
For high-volume HIPS trays, inserts and packaging products, a Thin-Gauge Thermoforming Machine can integrate processes such as:
Roll feeding
Heating
Forming
Cutting
Stacking
Important selection factors include:
HIPS sheet width
Sheet thickness
Product depth
Number of cavities
Mold dimensions
Required cycle speed
Cutting method
Target output
A stable production system should match the HIPS sheet, mold, heating system, forming process and cutting system rather than optimizing any one element independently.
HIPS stands for High Impact Polystyrene. It is a modified polystyrene material designed to provide greater toughness and impact resistance while remaining easy to process and thermoform.
Yes. HIPS has good formability and is widely used for thermoformed trays, packaging inserts, displays and appliance components.
A commercial HIPS thermoforming reference gives a typical forming range around 330–350°F (166–177°C), with approximately 340°F (171°C) as an ideal reference temperature. The correct temperature depends on the actual HIPS grade and sheet thickness.
HIPS combines good formability, impact strength, economical processing, easy cutting and useful surface options, making it suitable for many high-volume tray and packaging applications.
Yes. Print-grade HIPS sheets are available for screen, digital and offset printing. The surface specification and ink system should be confirmed before production.
Standard HIPS has relatively poor UV resistance, so it is generally not the first choice for prolonged outdoor exposure unless a UV-stabilized or weatherable system is used.
HIPS remains a widely used thermoforming material because it offers a practical balance of formability, toughness, process efficiency and cost.
It is especially attractive for trays, inserts and packaging products that do not require high transparency but do require reliable high-volume production.
HIPS also provides useful options for color, texture and printing, making it suitable for both functional packaging and visible retail products.
Its main limitations include relatively low UV resistance and lower optical clarity compared with PET or PETG.
For a new HIPS thermoforming project, the best results come from evaluating the sheet grade, thickness, mold geometry, forming temperature and thermoforming machine as one complete production system.
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