Vacuum Suction Cups for Hot Plastic Parts

Vacuum Suction Cups for Hot Plastic Parts: Material Selection Guide

Selecting vacuum suction cups for hot plastic parts requires more than checking a material’s maximum temperature.

The cup must establish a seal, support the workpiece during movement and release it reliably. At the same time, the plastic component may still be warm, relatively flexible or sensitive to contact marks.

For injection-molded parts and other heated plastic components, the main selection factors are contact temperature, exposure time, workpiece geometry, handling motion and downstream surface requirements.

NBR, HNBR, silicone and FKM can all be considered in appropriate conditions. The final choice depends on the specific compound and suction cup design.

EUROTECH offers material options across most existing suction cup designs using established compounds and molds, allowing customers to assess suitable versions without beginning with a new tooling project.

What Makes Hot Plastic Parts Difficult to Handle?

A plastic component can behave differently immediately after processing than it does after cooling.

Depending on the material, part geometry and process, it may be more susceptible to deformation at the point of gripping. Curved surfaces, ribs or narrow contact areas can also make it difficult to position a suction cup.

Other factors may include:

• Textured surfaces that affect sealing.
• Release agents or other residues.
• Thin walls that deflect under vacuum.
• Limited space for the gripping tool.
• Rapid movement between pickup and placement.
• Requirements for subsequent painting, printing or bonding.

Material selection is therefore one part of a larger gripping decision. A heat-resistant compound cannot compensate for an unsuitable contact position or cup shape.

Measure Contact Temperature and Exposure Time

The relevant temperature is the temperature where the suction cup touches the workpiece.

Plastic processing temperatures, mold settings and oven settings do not necessarily represent the surface temperature at pickup.

Establish the temperature at the intended contact area using a measurement method appropriate for the surface and process. Where conditions vary, capture the range rather than a single favorable reading.

Also record:

• Time between processing and pickup.
• Duration of each contact.
• Cycle frequency.
• Cooling time between contacts.
• Conditions after the equipment has been running continuously.

A cup that contacts a hot surface briefly and then cools may experience different conditions from one that remains in contact for longer periods.

Repeated cycles can also change the temperature of the cup itself. A trial performed only at machine startup may not represent normal production.

Choosing Between NBR, HNBR, Silicone and FKM

Material selection should begin with the actual operating conditions and the specifications of the candidate cup.

NBR for suitable operating temperatures

Not every plastic component requires a special high-temperature material. If the part has cooled sufficiently and the compound meets the exposure conditions, NBR may provide a practical solution.

HNBR for more demanding thermal conditions

HNBR can be evaluated when the existing NBR cup loses flexibility or ages too quickly under the operating conditions.

It should still be tested for sealing, deformation and surface effects on the actual plastic component.

Silicone where flexibility and temperature resistance are useful

Silicone is frequently considered for heated workpieces and applications requiring flexible contact.

However, processes with painting, printing or bonding requirements should review their restrictions on silicone and other potential contaminants. Suitability must be assessed against the actual downstream process.

FKM for specific temperature and chemical requirements

FKM may be useful where particular thermal or chemical conditions justify its selection.

It should not be chosen solely on the assumption that a more specialized material will grip better or leave fewer marks.

For detailed guidance on these three elastomers, read our NBR, HNBR and FKM suction cup material comparison. If silicone is also being considered, see our NBR vs silicone comparison.

Flat, Oval or Bellows: Match the Cup to the Part

The shape of the suction cup should match the available contact area and the movement required during pickup.

Flat suction cups

Flat cups are candidates for relatively flat contact areas where stable positioning is important and limited height compensation is needed.

The supporting geometry and cup size should be appropriate for the stiffness of the warm plastic component.

楕円形吸着パッド

Oval cups can be useful when the available contact region is long and narrow.

Before selecting one, check that the entire sealing perimeter fits within the usable area and does not cross an edge, rib, opening or pronounced texture.

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Bellows designs may help where height variation or additional compliance is required.

Their movement and deformation must be considered when handling a soft or thin-walled component, particularly during acceleration and placement.

Browse EUROTECH flat suction cups and oval suction cups to compare existing design options.

Reduce Deformation and Evaluate Surface Marks

A circular mark after handling does not necessarily mean that material has transferred from the suction cup.

The result may involve local deformation, contact pressure, relative movement, residue or a combination of factors.

When evaluating surface quality, check:

• The location of the cup on the component.
• Workpiece stiffness at pickup.
• Cup support and contact area.
• Vacuum level and contact duration.
• Movement between the lip and the surface.
• Cleanliness of the cup and workpiece.
• The appearance after the part has cooled.

A harder cup does not automatically prevent marks. A softer cup does not automatically protect a delicate surface. The result depends on the interaction between the material, geometry and process.

For thin parts, assess whether a different contact location or distribution of gripping points can reduce localized deformation. Any change must still provide adequate holding performance for the handling motion.

Check Painting, Printing and Bonding Requirements

If the plastic component will be painted, printed, coated or bonded, specify this at the beginning of the selection process.

Three requirements should be distinguished:

• Restrictions on silicone or other substances.
• Absence of unacceptable visible marks.
• Compatibility with the downstream process.

Meeting one requirement does not automatically establish the others.

For example, a cup made from a non-silicone elastomer should not automatically be described as free of all substances that could interfere with painting. Likewise, a part with no visible contact mark may still need downstream process testing.

Evaluate handled samples through the relevant painting, printing or bonding process, using the customer’s acceptance criteria.

Material Options Using Existing EUROTECH Molds

Most EUROTECH suction cup designs can be produced in alternative material versions using established compounds and existing molds.

Available design families include 200 PK, 280 PK, R, RL, A, B and CO flat suction cups, along with oval types.

This broad range makes it possible to begin with an existing geometry and assess a material version suited to the application.

However, not every design is appropriate for every plastic part.

Small contact areas require suitable dimensions. Larger cups such as 200 PK or 280 PK should only be considered where the workpiece provides sufficient usable contact area and support.

The selection should confirm:

• Contact footprint.
• Cup height and available installation space.
• Mounting and connection.
• Material and hardness.
• Workpiece temperature.
• Handling direction and motion.

Learn more about EUROTECH custom suction cups and existing-design material options.

Validate the Cup Under Production Conditions

A practical evaluation should cover pickup, movement, release and the effect on the finished component.

1. Document the application

Record the plastic type, weight, geometry, contact temperature and cycle.

Include information about textures, release agents and downstream finishing.

2. Select candidate designs and materials

Choose a cup that fits the available area and a compound that matches the temperature and exposure requirements.

3. Check pickup and release

Confirm that the cup establishes a seal within the available cycle time and releases the part without dragging or unwanted deformation.

4. Evaluate the full handling motion

Test the intended orientation, acceleration, movement and placement conditions.

For injection-molding applications, distinguish transporting a released component from overcoming mold retention or other extraction forces. Those forces must be assessed as part of the machine process.

5. Inspect after repeated cycles

Check cup condition, leakage, deformation and changes in handling behavior after sustained operation.

6. Inspect the finished workpiece

Evaluate the component after cooling and, where relevant, after painting, printing or bonding.

7. Record the outcome

Document the selected model, material, operating conditions and acceptance results so that the approved configuration can be reproduced.

よくあるご質問

Which temperature should I use when selecting the cup?

Use the temperature at the actual suction cup contact area, together with contact duration and cycle conditions.

Can HNBR suction cups be used for injection-molded parts?

HNBR can be considered, but suitability depends on the compound, geometry, surface and operating conditions.

Should silicone always be avoided before painting?

Review the requirements of the specific painting process. Where silicone is restricted, confirm the relevant material and handling requirements and validate the result.

Will increasing vacuum solve slipping or unstable pickup?

Not necessarily. Sealing, geometry, surface condition and movement may be the underlying causes. Higher vacuum can also change deformation of a thin component.

Does a special material require a new mold?

For most existing EUROTECH suction cup designs, alternative material versions can be evaluated using established compounds and existing tooling. Product-specific details are confirmed during selection.

Discuss Your Hot Plastic Handling Application

Send EUROTECH a photograph or drawing of the component, its weight, the available contact area, pickup temperature and cycle details.

Please also indicate whether the part will be painted, printed, coated or bonded.

We can review suitable existing suction cup designs and material options for application testing.

Contact EUROTECH about suction cups for hot plastic parts.