SMC MHF2-12D Low Profile Air Gripper 12 mm Bore

A thin gripper with a double-piston drive

MHF2-12D is a double-acting low-profile air gripper from the SMC MHF2 series. Its two pistons act on a rack-and-pinion mechanism, which keeps the body only 25 mm high yet gives a 48 N gripping force in the catalogue comparison. The catalogue sets it against the MHZ2-20D, which gives 42 N but is 72.8 mm tall; for a machine with a tight vertical envelope that height saving of roughly 48 mm is the main attraction.

The code reads MHF2 for the series, 12 for the 12 mm bore and D for double acting. The MHF2 range is built in bore sizes 8, 12, 16, 20, 25 and 32 mm; the catalogue also lists short, medium and long stroke variants selected by a suffix on the model number, and this code is the basic double-acting 12 mm model.

Technical specifications

Why the repeatability figure is different from a cam gripper

The rack-and-pinion drive has some backlash, so repeatability is +/-0.05 mm only when no offset load is applied, rising to +/-0.15 mm with an offset load. A part that needs gripping repeatability of +/-0.01 mm is better served by a cam-type or wedge-type gripper such as the MHZ2 series; the MHF2 is chosen for space and for a good ratio of grip force to size.

The catalogue publishes allowable-moment and gripping-point data for each bore, and these should be checked with the actual finger attachments in place, because long or heavy attachments quickly use up the margin and add to the offset load that degrades repeatability.

Mounting and use

The thin body suits parts feeders, compact pick-and-place axes and cobot or SCARA wrists with limited depth. Use clean, filtered and dry air, throttle the exhaust and keep the finger attachment light. Auto switches can be fitted for open and closed position feedback. The catalogue includes a worked selection example that chooses the MHF2-12D: with a required gripping force of 29.4 N at an operating pressure of 0.4 MPa, a gripping force of 38 N satisfies the requirement, which shows how the catalogue expects the effective force at the working pressure, not the headline value, to be compared with the load.

Key features of the MHF2-12D

• Low-profile body only 25 mm high, the main reason to choose it over a standard parallel gripper.
• Double-piston rack-and-pinion drive giving 48 N in the catalogue comparison.
• Double acting: air pressure drives the fingers both to open and to close.
• Operating pressure of 0.15 to 0.7 MPa for the 12 mm bore.
• Non-lube operation and an ambient range of -10 to 60 °C.
• Up to 120 cycles per minute for short and medium strokes.
• Mounting for auto switches to confirm open and closed positions.

How to size the gripper

Gripper selection follows the same steps as the catalogue example. First work out the gripping force needed: for a friction grip this depends on the workpiece mass, the friction coefficient between finger and part, and a safety factor for acceleration of the robot or axis. Next, read the effective gripping force from the catalogue graph at the actual supply pressure and at the gripping point distance of the finger attachment, not the headline value. Finally, check the external moments and loads on the fingers against the allowable values. If any check fails, consider a larger bore or a lighter attachment.

Designing finger attachments

• Keep attachments short and light, since mass and length both increase the moments on the fingers and the offset load that affects repeatability.
• Machine the gripping faces to the part shape where possible, so the part is located rather than only clamped.
• Use the finger mounting threads and torque values given in the catalogue.

Air supply and maintenance

Supply clean, dry air through a filter regulator, and use speed controllers to limit finger speed, which reduces impact on the part and on the mechanism. In hot and dusty plants such as many in Oman and the GCC, compressed air often carries more moisture and particles because of high intake temperature, so good filtration and a dryer are important to keep the seals in condition. Keep the gripper within its 60 °C ambient limit and shield it from direct radiant heat.

Typical applications

Low-profile grippers such as the MHF2-12D are used to pick small components in electronics and assembly lines, to transfer parts between stations on compact indexing machines, and to handle caps, inserts and small moulded parts in packaging and plastics plants, where the short body keeps the overall tool height and the moving mass low.

What to include in an RFQ

Give the full model code including any stroke suffix, the quantity, the auto switch model and lead length if switches are needed, and the operating pressure available, so the gripping force can be checked against your application.

Documents and quotation

The SMC MHF2 catalogue PDF is linked for specifications, model selection and dimensions. Please confirm stroke variant, finger attachment design and switch requirements before ordering. See also Pneumatic Cylinders. Seven Star LLC is an independent supplier and provides quotes for the exact code on request.