Pinch Grips

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 17, 2026

Pinch and pincer grips grab a small area of a product the way two fingers do, so a tensile tester or universal testing machine can pull on it and record the force. They are the grips for product tests rather than material coupons: peeling a lid off a tray, pulling a freshness seal, tugging a bag handle, lifting a latch, pulling a component off a circuit board, or checking that a button, snap, crimp terminal or wire stays attached. Universal Grip builds spring-loaded pinch grips, screw-actuated pincer grips in small, wide and large sizes, a pneumatic pincer grip, and a family of special-purpose pinch-type grips (button pull-off, tweezer, wire terminal, drill chuck and pin vise), with a chain accessory that self-aligns the pull.

This page explains the difference between pinch and pincer actuation, how to pick a size and jaw style, what each grip in the range holds, the standards and product tests they serve, how they mount to any machine, the setup habits that make pull-off results repeatable, and the mistakes that produce low or scattered numbers. For material-coupon grips (wedge, pneumatic, roller, vise), start from the tensile grips range or the grip selection guide.

In this guide: What Pinch and Pincer Grips Do · How to Choose a Pinch Grip · The Pinch and Pincer Grip Range · Tests and Standards Served · Machine Compatibility · Setup and Best Practices · Common Mistakes · Related Products · FAQ

What Pinch and Pincer Grips Do

Most tensile grips need a flat tab or a round end to hold. A pinch-type grip needs almost nothing: two small jaws close on an edge, a flap, a seal, a wire or a component lead and pull it in the direction the machine moves. Because the gripped area is small and the grip itself is light, the test measures the attachment or bond, not the grip. That is why pinch grips are used for end-consumer products, whose failures are pull-offs and peel-offs rather than coupon fractures.

The two actuation styles behave differently, and the names are often mixed up:

• Pinch grips are spring-loaded. The spring exerts a constant lateral force on the sample, and turning the knob at the end of the grip tensions the spring to raise or lower the pinching force. The jaws close on the sample as soon as it is released, which makes loading fast and the clamping force the same every time.

• Pincer grips use a vise screw. Turning the screw closes the two sides on themselves, so the clamping force is set by the operator and can be high for the size of the jaw. The slim nose gets into tight spaces, which is why pincer grips are the usual choice for pull-off testing of components on printed circuit boards. Pneumatic versions of the pincer style are also available for a constant, air-set clamping force.

Both are used on small-capacity frames such as the Mark-10 tensile testers and on benchtop universal testing machines in packaging, medical device, consumer goods, apparel, electronics and automotive labs, and both pair with peel fixtures when the test is a peel rather than a straight pull.

How to Choose a Pinch Grip

Match the grip to the force, the opening and the space around the gripped feature, in that order.

• Force. The small pincer grip holds about 100 N (around 20 lbf), the wide pincer about 500 N, and the large and pneumatic pincer grips about 2 kN (around 400 lbf). Choose the lightest grip that covers the expected peak force; a 95 g grip on a 100 N test keeps the moving mass and the tare small for a low-capacity load cell.

• Opening and jaw size. The small pincer opens to 4 mm; the large pincer opens 0 to 10 mm with a 1 × 1 in clamping surface. Measure the thickness of the flap, seal or lead and the size of the area you can grip without touching the rest of the product.

• Access. For a component on a crowded board or a tab inside a tray rim, the slim nose of a small pincer or the long jaws of the tweezer grip reach where a square jaw cannot. For a bag handle or a container latch, the wide pincer's curved, finger-like ends wrap the feature.

• Clamping style. Spring-loaded pinch for fast, repeatable loading at a set force; screw pincer when you need to adjust force per specimen or bite hard on a small area; pneumatic pincer when many operators run the same test and the clamping force must not depend on who tightened the screw.

• Jaw faces. Serrated or pyramid faces (large pincer) hold tapes, laminates and coated surfaces; smooth or curved ends (wide pincer) avoid cutting soft plastics and films.

• Alignment. Add the chain accessory when the gripped feature is not on the load axis or the product cannot be held square; the chain lets the pull find its own line and gives the operator slack to position the grip.

If the feature is round (a pin, a rod, a wire, a small bolt), skip the pinch styles and use the drill chuck or pin vise grip, which centre the specimen on the load axis; if it is a button, snap or crimp terminal, use the purpose-built grip below.

The Pinch and Pincer Grip Range

Small pincer grip

The small pincer grip holds about 100 N (around 20 lbf) with a maximum opening of 4 mm. It is made of hardened steel and weighs 95 g, so it adds almost no tare on a low-capacity load cell. The end of the grip can be fastened to a chain for self-alignment, or attached directly to a female adapter coupling on the machine.

Wide pincer grip

The wide pincer grip is for slightly larger samples and works well for handles on bags and latches on containers. Its end pieces are curved, like the last joint of a finger, and can be changed to straight ends. The grip works to about 500 N and weighs 180 g.

Pneumatic pincer grip

The pneumatic pincer grip is one of the strongest pinch-type grips because air pressure keeps the sample restrained: it applies a horizontal gripping force of 2 kN. Pneumatic grips are easy to install, give every operator the same clamping force, and help to accelerate and automate laboratory testing. See pneumatic grips for the air supply and foot-pedal options that drive them.

Large pincer grip

The large pincer grip is the biggest in the range and holds about 2 kN (around 400 lbf). The opening is 0 to 10 mm with a 1 in × 1 in clamping surface, and the inside faces carry a serrated or pyramid pattern. Besides product pull tests it is a good grip for tensile pulls on tapes and adhesive laminate coatings.

Pinch grip with chain

The chain can be added to the end of any pincer or pinch grip. It aligns the tensile force with the gripped feature and makes mounting easier: the operator puts some slack in the chain, manoeuvres the grip to the right spot on the sample, and lets the machine take up the slack. The photo on this page shows a pinch grip with a chain pull-testing a freshness seal, and the video shows an ASTM F2824 tensile test on a flexible peelable lid using a pinch grip with a 90° peel fixture.

Button pull-off pinch grip

The button pull-off pinch grip clamps the body of a button, snap or small fastener while the garment is held below, so you can measure the force needed to pull it off, as in button and snap attachment safety tests for children's wear.

Tweezer grip

The tweezer grip has long, slim jaws for holding very small or delicate specimens such as fine wires, fibers, sutures and electronic leads in tight spaces where a pincer nose will not fit.

Wire terminal grip

The wire terminal grip uses a slotted rotating disc to hold crimped terminals and connectors of different sizes, for crimp pull-out and terminal retention testing. Rotate the disc to the slot that fits the terminal, drop the wire through, and pull.

Drill chuck grip

The drill chuck grip uses a keyless chuck to hold round specimens such as pins, rods, wires and small bolts centered on the load axis, which a pinch jaw cannot do with a round part.

Pin vise grip

The pin vise grip holds very fine round specimens, such as needles, thin wires and pins, in a small collet for low-force tensile and pull-out tests.

Tests and Standards Served

Pinch grips rarely appear by name in a standard; the standard defines the product and the pull, and the grip is whatever holds the feature. These are the tests they are bought for:

• Peelable lids and seals: ASTM F2824 (tensile test of flexible peelable lids on containers) with a pinch grip and the 90° peel fixture; freshness-seal and tamper-band pulls with the chain.

• Heat seals and pouches: ASTM F88 seal strength when the seal tab is too short or too stiff for a standard grip; ASTM F1306 and D3787 belong to the puncture fixtures, not to grips.

• Tapes and laminates: 180° and 90° peel per ASTM D3330 and ASTM D903 when the free end is gripped with the large pincer's serrated faces.

• Buttons, snaps and fasteners: button pull-off testing for children's clothing per the apparel industry's attachment-strength practices and the 16 CFR 1500 small-parts requirements, with the button pull-off grip.

• Wire and terminal retention: crimp pull-out and terminal retention tests to UL and SAE/USCAR crimp specifications, with the wire terminal grip; fine-wire and fiber tensile per ASTM D3822 with the pin vise or tweezer grip.

• Electronics: pull-off of surface-mount components, connectors and leads from printed circuit boards with the small pincer or tweezer grip.

• Consumer products: bag handles, container latches, labels, zipper pulls, cords and closures, where the pull is a product specification rather than a published standard.

Garment and textile seam strength (ASTM D1683) and fabric grab tests (D5034) use wider jaws; see the textiles page and vise grips for those.

Machine Compatibility

Every pinch and pincer grip mounts through a female adapter coupling, a clevis pin or the chain, so it fits any brand of tester. On a Mark-10 or other small frame the grip attaches to the force gauge or the base with the standard small coupling; on a benchtop universal testing machine it mounts through the machine's adapter. The lower end of the setup is usually a flat plate, a vise grip or a peel fixture holding the product body, and the pinch grip hangs from the load cell.

Because these are low-force tests, pair the grip with a load cell sized to the expected pull: a 100 N or 250 N cell for seals and small components, 500 N to 1 kN for handles, latches and buttons, and 2 kN or more only for the large and pneumatic pincer grips at their limit. A 5 kN cell reading a 15 N seal pull is working at 0.3 % of range and will not resolve the result. Our Mark-10 tensile testers from 100 lb upward and the 2.5 kN benchtop UTM cover the range.

Setup and Best Practices

• Grip the same feature the same way every time. Mark the grip position on the first specimen (a set distance from the seal edge or tab end) and keep it; pull-off force changes with where you pinch.

• Set the pinch force once. On spring pinch grips, tension the knob until the jaws hold without slipping on a trial pull and leave it; on pincer grips, note the screw position. Changing the clamping force between specimens changes the result.

• Use the chain when the product cannot be held square. It removes side loads that would otherwise show up as a higher, scattered force, and it lets the operator place the grip precisely.

• Hold the product body rigidly. The grip measures the feature; the rest of the product must not move, flex or lift. A plate clamp, a vise grip on the body or the base of a peel fixture does that job.

• Match speed to the standard or the product spec, and keep it constant across specimens; peel and pull-off forces are rate dependent.

• Watch for jaw slip and jaw cut. A trace that plateaus before the feature releases is slip (more clamping force or serrated faces); a feature that tears at the jaw is a cut (smooth or curved ends, less force).

• Zero the load with the grip hanging so the grip and chain weight are not in the reading.

Common Mistakes

• Using a large pincer grip on a 10 N seal, so the tare and the serrations dominate the result.

• Gripping a different amount of the tab or flap on each specimen.

• Pulling off-axis without the chain, which adds a side load the test does not intend.

• Serrated faces on thin film, which cut the specimen at the jaw instead of peeling the seal.

• Letting the product body lift or flex because it is only held by hand or a loose plate.

• A load cell many times larger than the pull, so the reading is a few counts of resolution.

• Calling a lid test a 'peel' and a seal test a 'pull' without fixing the angle; use the 90° fixture when the standard, such as F2824, requires it.

Related Products

• Peel fixtures: 90° sliding table, 180°, floating roller and climbing drum for peel geometries.

• Vise grips and pneumatic grips for the product body or wider tabs.

• Puncture fixtures for packaging puncture and burst tests.

• Bollard grips and rope grips for cords, threads and wire.

• Mark-10 tensile testers and benchtop universal testing machines.

• Adapters and couplings for any machine brand; the grip selection guide for the full grip range.

Pinch Grip FAQ

What is the difference between a pinch grip and a pincer grip?

A pinch grip is spring-loaded: the spring applies a constant lateral force and a knob tensions it to adjust the pinching force. A pincer grip closes with a vise screw, so the operator sets the clamping force; its slim nose reaches into tight spaces such as component leads on a circuit board. Pneumatic pincer grips use air pressure instead of a screw.

What force can pinch grips hold?

The small pincer grip holds about 100 N (20 lbf), the wide pincer about 500 N, and the large pincer and pneumatic pincer grips about 2 kN (400 lbf). Choose the lightest grip that covers the expected peak force.

How wide do the jaws open?

The small pincer grip opens to 4 mm; the large pincer grip opens from 0 to 10 mm with a 1 × 1 in clamping surface. Ask for the cut sheet for the other models.

What is the chain for?

The chain attaches to the end of any pinch or pincer grip and aligns the pull with the gripped feature. It also makes mounting easier: the operator puts slack in the chain, positions the grip on the sample, and the machine takes up the slack as the test starts.

Which grip do I use for a peelable lid test?

ASTM F2824 tensile tests on flexible peelable lids use a pinch grip on the lid tab with a 90° peel fixture holding the container, as shown in the video on this page.

Can pinch grips test buttons and snaps?

Yes. The button pull-off pinch grip clamps the body of a button, snap or small fastener while the garment is held below, to measure the force needed to pull it off in attachment safety tests.

Which grip holds crimped wire terminals?

The wire terminal grip, which uses a slotted rotating disc to hold crimped terminals and connectors of different sizes for crimp pull-out and terminal retention tests.

Which grip holds round pins, wires and small bolts?

The drill chuck grip uses a keyless chuck to hold rods, pins, wires and small bolts centered on the load axis; the pin vise grip holds very fine needles and wires in a small collet for low-force tests.

Will pinch grips fit my Mark-10 or Instron machine?

Yes. The grips mount through a female adapter coupling, a clevis pin or the chain, so they fit Mark-10 force gauges and test frames as well as universal testing machines from Instron, MTS, Shimadzu, ZwickRoell, Galdabini and others through the matching adapter.

What load cell should I use with a pinch grip?

Size the cell to the pull, not the machine: 100 to 250 N for seals and small components, 500 N to 1 kN for handles, latches and buttons, and 2 kN only for the large and pneumatic pincer grips near their limit.

Need a pinch or pincer grip for a product pull test? Contact Universal Grip with the product, the feature you need to pull, the expected force and your machine's make and model, and we will quote the grip, chain and adapter as one setup.