Pneumatic Sheet Bending Machine

Small workshops and college fabrication labs bend sheet metal with hammers, bench vices or hand brakes — slow, inconsistent, and hard on the operator for anything beyond a one-off bracket. This project builds a compact pneumatic press brake: a double-acting pneumatic cylinder mounted on a welded C-frame drives a punch into a V-die, folding sheet strips (aluminium or mild steel) to a repeatable angle. A 5/2 hand-lever valve gives the operator direct push–pull control, an FRL unit (filter–regulator–lubricator) keeps the air clean and the pressure set, and adjustable stops and a back gauge position each bend. The student fabricates the frame, sizes the cylinder from the required bending force, plumbs the pneumatic circuit, and demonstrates repeat bends on real sheet — a complete, demonstrable manufacturing machine built from standard industrial components.

1. Set the working pressure on the FRL regulator (design target: 6 bar shop air) and confirm the gauge reading.
2. Place the sheet strip on the V-die against the back gauge, positioning the bend line under the punch.
3. Shift the 5/2 hand-lever valve to extend — the cylinder drives the punch down into the V-die, folding the sheet.
4. The punch stops on the adjustable angle stop; hold briefly, then shift the valve to retract the cylinder.
5. Remove the bent strip, check the angle with a protractor, and adjust the stop if a different angle is needed.
6. Repeat the cycle on successive strips to demonstrate consistent bend angle and flange length across the batch.
7. Compute the theoretical bending force from cylinder bore × line pressure and compare with the sheet's bend requirement from standard bending-force data.

Tech stack:

• Double-acting pneumatic cylinder
• 5/2 hand-lever directional control valve
• FRL unit with pressure gauge
• Hardened punch and V-die set
• Welded MS C-frame
• Adjustable back gauge and angle stops
• PU tubing and push-in fittings
• Shop air compressor (external supply)

• [Cylinder-driven V-die bending] A double-acting pneumatic cylinder drives a hardened punch into a V-die, producing clean air-bends in sheet strips up to the rated width.
• [5/2 hand-lever control valve] Direct manual control of extend and retract — simple, transparent and standard industrial practice for small presses.
• [FRL unit] Filter, regulator and lubricator condition the shop air and set working pressure, with a gauge showing the set pressure during every bend.
• [Adjustable angle stops] Mechanical stops limit punch travel so bend angle repeats across parts — the student demonstrates consistency across a batch of strips.
• [Back gauge] An adjustable fence positions the sheet for consistent flange length on repeated bends.
• [Force sized from first principles] Cylinder bore is selected from the required bending force (pressure × piston area); the report shows the sizing calculation as a design-target figure.
• [Welded C-frame] A rigid MS C-frame carries the cylinder and die set with the working area open at the front for easy loading.
• [Two-hand safe working] The valve placement and guarding keep hands clear of the die during the stroke.

• Fabricated machine: C-frame, punch, V-die, back gauge, stops
• Double-acting pneumatic cylinder
• 5/2 hand-lever valve and FRL unit with gauge
• PU tubing, fittings and silencers
• Pneumatic circuit diagram and sizing calculations
• Operating procedure and safety notes
• Project report PDF (pneumatics theory, design, procedure)
• PPT presentation for final review
• Viva Q&A preparation document

• The 1.2–1.9 kN force is a theoretical design-target calculation (pressure × piston area); actual delivered force is lower due to seal friction and is not claimed as measured.
• Sheet capacity is a design target — thicker or harder stock (stainless) is outside the machine's range.
• Needs an external compressor delivering 6–8 bar; the compressor itself is not included.
• Bend angle depends on operator stop-setting and springback of the material; the student characterizes springback on their own samples.
• Pneumatic exhaust is noisy without silencers; silencers are fitted but the machine still needs a ventilated workspace.