Key takeaways
- Use 3.0 mm plate for M32 glands and larger, and 2.0 mm only up to M25; a 1.6 mm plate bows under gland torque and opens the sealing washer.
- Hold cutout diameter to gland thread +0.3 mm and hole-to-edge distance at 1.5 × cutout diameter, or the sealing land tears and the joint leaks.
- Cut, deburr, pretreat and coat in that order; a gland hole cut into a finished panel starts rusting within one monsoon.
- Above roughly 2,000 panels a year a blanking tool beats laser time; below 500 panels the 12 kW fibre laser is the cheaper route.
A genset cable entry panel is the smallest panel on a canopy and the one most likely to let water, dust or a rodent into the alternator compartment. Genset cable entry panel manufacturing is decided by three numbers: gland thread size, plate thickness and panel flatness. The failure is almost never the steel. It is the clearance between cutout and gland, the flatness of the plate under gland torque, or an edge that was cut after the paint went on.
A 1,250 kVA canopy might carry six M32 and twelve M20 glands. Four-core 240 mm² copper cable weighs about 2.4 kg per metre, so a 15 m drop from a cable tray puts roughly 36 kg of static load on a single gland body. That load, plus the sealing torque the fitter applies, hangs on a plate that is usually 2.0 mm CRCA bolted to a 1.6 mm canopy skin. Genset cable entry panel manufacturing is a thickness, flatness and sequence problem before it is a cutting problem.
What follows is the route we run for Mahindra Powerol canopy work, the dimensions that decide whether the panel seals, and where the route stops being the right one.
What fails first on a cable entry panel?
Water tracking through an oversized cutout comes first, then plate distortion under gland torque. Both are settled on the drawing, months before anyone torques a gland.
A gland seals on a flat land roughly the width of its washer, about 6–8 mm for an M20 and 10–12 mm for an M32. If the laser leaves a 0.3 mm burr on the underside, or the plate is bowed 0.5 mm across a 200 mm span, the washer touches on one side only. The joint feels tight and passes a bench check. It starts weeping after a season because the powder film relaxes and the plate relaxes with it.
The second failure is thermal. A canopy roof reaches 65–75 °C in direct sun in Vidarbha or coastal Maharashtra while the shaded underside sits near ambient. A 2.0 mm plate restrained at four bolts with an M32 cutout in the middle will oil-can. The gland follows the plate, the seal opens on the tension side, and the first monsoon finishes the job.
The third failure is entry itself. A 1.6 mm knockout with an open grommet is a rat door, and a rat inside a canopy will strip the alternator leads. A closed gland plate with no unused holes is the reliable answer. A spare hole with a threaded blind plug is acceptable only when the plate is 3 mm thick.
The dimensions that decide whether the panel seals
The table is the specification we ask for on a canopy drawing. The middle column is what the drawing should state. The right-hand column is what we hold in production, and where we would push back.
| Parameter | What the drawing should state | Ganesh practice or limit | Why it matters |
|---|---|---|---|
| Panel material | CRCA to IS 513, D or DD grade; or galvanised to IS 277 | CRCA 1.6–2.0 mm; galvanised 2.0 mm on request | D grade bends at 2 mm and R2 without splitting |
| Plate thickness at gland | 2.0 mm to M25; 3.0 mm from M32 up | 1.6 mm minimum, 3.0 mm standard above M25 | The gland washer needs a stiff land |
| Cutout diameter | Gland thread +0.3 mm, H12 | ±0.2 mm laser, ±0.5 mm finished position | 0.5 mm oversize gives a line-contact seal |
| Hole-to-edge distance | At least 1.5 × cutout diameter | Held in nesting; flagged at drawing review | Under 1.5D the land tears under torque |
| Hole pitch | Cutout diameter + 8 mm minimum | Checked against the gland body hex | Gland bodies foul before the holes do |
| Thread form | ISO metric, M16 to M63 | M16–M50 standard, larger by agreement | Mixed PG and metric threads cause field returns |
| Return flange | 15 mm minimum, single fold | 15 mm at 2.0 mm; 20 mm at 3.0 mm | A 12 mm flange needs a 10 mm V and marks the face |
| Panel flatness | 1.0 mm over 500 mm | ±0.5 mm typical; 1.0 mm over 500 mm | Bow under torque opens the seal |
| Inside bend radius | 1.0 t minimum | R2 at 2.0 mm; R3 at 3.0 mm | Below 1t the outer fibre necks |
| Coating | Polyester powder, 60–80 µm DFT | 60–80 µm over seven-tank pretreatment | Under 60 µm, salt spray life falls sharply |
| Edge condition | All cut edges deburred | Deburred before pretreatment | Burrs trap chemical and blister in the oven |
Two rows matter more than the rest. Plate thickness and flatness together decide the seal; everything else decides whether the fitter can assemble the panel in a reasonable time. If you are choosing between a stiffer plate and a heavier skin, choose the stiffer plate and add a rib.
Blank to packed panel: the route in five steps
The route is short, but the order is fixed. Changing the order changes the part.
Nesting and blanking
The 12 kW fibre laser on a 40 ft × 16 ft bed cuts entry plates alongside louvre blades and door skins from the same 2.0 mm CRCA sheet. Kerf is about 0.3 mm, so a 2.0 mm hole can be cut cleanly and a 1.0 mm hole cannot. Holes below 1.0 t are punched on the 250 T press or drilled after cutting. For one canopy programme we nest the plate with the base frame gussets, which keeps the remnant usable for the next bracket. See how nesting reduces sheet metal cutting cost for the arithmetic on remnant value.
Volume changes the choice. Under roughly 500 panels a year, laser is cheaper because there is no tool. Above roughly 2,000 panels a year, a blanking tool usually wins on piece price. Between those numbers it depends on how many cutouts are in the plate, because every hole is laser time. We quote both routes when the quantity sits in that band.
Forming
The 200 T, 5-axis brake with a 4,450 mm bed folds the two long return flanges and any stiffening jog. CRCA at R2 on 2.0 mm behaves close to a K-factor of 0.44, which is what our flat patterns assume. If your DXF was flattened with a different K-factor, the blank arrives short by around 0.4 mm per bend at 2 mm and the flange height drifts. Send the folded model rather than the flat, and we will confirm the developed length. The bend allowance method sets out the arithmetic.
Welding the gland plate
Where the drawing calls for a separate gland plate, we weld it to the skin with 25 mm stitches at 60 mm pitch and a continuous run along the top edge only. Continuous welds on all four sides pull the plate into a saddle of 0.8–1.2 mm. Stud or rivet fixings are better where the gland load is light, and they keep the panel flat for powder.
Weld spatter on the sealing land is the common defect at this stage. It is removed before pretreatment, not after, because blasting a coated panel is not a repair.
Pretreatment and coating
Panels pass the seven-tank line: degrease, rinse, descale, rinse, conversion coating, rinse, deionised rinse, then dry-off and powder. Threads are plugged with silicone, not tape, because tape residue survives the oven. Coating is 60–80 µm polyester, measured with a DFT gauge on a flat area and on a flange, since the two rarely match. The seven-tank pretreatment process explains why the conversion coat stage decides the salt spray result more than the powder brand does.
First article and packing
The first article includes a gland fit check with the customer's own gland, not a sample from our store, because sealing washers differ by supplier. We record cutout diameter, flatness, DFT and adhesion by cross-hatch to ISO 2409. Panels are packed face to face with a separator so the flange edges do not chip in transit.
Where the tolerance budget goes
Three tolerances stack on a cable entry panel: the cutout position on the panel, the panel fixing holes, and the frame holes the panel bolts to.
Take a 1,200 mm wide panel with an M32 cutout at the far end. The cutout sits within ±0.2 mm of nominal. The panel's fixing holes are ±0.5 mm. The frame bracket holes are ±1.0 mm. Worst case, the cutout lands 1.7 mm from where the cable schedule expects it, and the cable has to be pulled sideways to reach the gland. That is where a 12 × the cable diameter bend radius disappears.
The fix costs nothing. Specify 14 × 18 mm slots for M10 fixings instead of 11 mm round holes, and the assembly absorbs 4 mm of stack in one direction. Keep the cutout as the datum, dimension the fixing holes from it, and do not dimension both from an outside edge.
The same logic applies to the bend. A 90° bend at 2.0 mm with R2 and a K-factor of 0.44 has a bend allowance of 4.52 mm; the same bend flattened at K 0.33 gives 4.16 mm. Over four bends the two flat patterns differ by 1.4 mm, which is enough that the fixing slots no longer line up with a frame drilled to the other convention. We work to K 0.44 at this thickness, and the bend allowance calculator reproduces the figure.
The rework we actually see on entry panels
Three defects account for most of the rework on this part family, and none of them is a machining problem.
Oversized cutout. A designer specifies a 32.8 mm hole for an M32 gland because the drawing says "clearance for fitting". The gland washer covers the hole, so it looks fine, but the sealing land shrinks by 0.25 mm all round and the ligament at the nearest corner drops below 1.5D. Retrofitting means welding a patch into a coated panel, which is a repaint, not a repair.
Flange too short for the die. A 15 mm return on 2.0 mm CRCA bends in a 16 mm V at roughly 16 t per metre of bend. Set the flange at 12 mm and the die has to close to a 10 mm V, which pushes the force to about 26 t/m, marks the outside face at the punch nose and risks a crack at the corner. Three millimetres of extra material removes both risks.
Coating build on the gland land. Powder wraps around a cutout edge and adds 20–30 µm on the land, so the gland washer sits on film rather than steel. Film creeps under sustained load at 70 °C, the torque is lost, and the joint loosens. Either mask the land or specify a toothed washer; the drawing should say which.
Each of these is a drawing decision worth seconds and a production consequence worth a repaint. That is the argument for a manufacturability review before the first blank, which is what our laser cutting capability team does when a canopy package arrives.
What Ganesh runs for canopy cable entries
Cable entry panels for canopies come off the 12 kW fibre laser, are formed on the 200 T brake to 10 mm, welded on the three CLOOS robotic MIG cells or one of the 30-plus manual stations, and coated on the seven-tank line with an 18 ft × 14 ft powder booth. Inspection uses a DFT gauge and cross-hatch adhesion testing, and PPAP with first article inspection is available where the programme needs it. The plants run to ISO 9001:2015 and ISO 14001:2015.
Mahindra Powerol is the canopy reference on our list, and the Powerol work is where most of our louvre, door and entry panel experience comes from. The genset and canopy guides carry the frame, door and louvre routes that sit either side of this panel. We do not publish measured sound levels for canopies. Noise performance is a property of the assembled genset and is measured by the OEM to ISO 8528-10; supplying a number would be inventing a test result.
What the canopy drawing has to settle
- Panel material and grade, with the sheet standard (IS 513 D, or IS 277 for galvanised).
- Plate thickness at the gland, called out separately from the skin thickness.
- Gland schedule: thread size, quantity, cable outside diameter and cable weight per metre.
- Cutout diameter as nominal +0.3 mm, with the position tolerance.
- Required IP rating to IEC 60529, and whether the test is on the panel alone or the assembled canopy.
- Coating system, colour, DFT range and the salt spray hours you expect, to ISO 9227.
- Flatness limit and the surface it is measured on.
- Masking instruction for threads, earth studs and mating faces.
The canopy RFQ checklist covers the same fields for the whole enclosure, including louvres and doors.
When this route is not the right one
Hot-dip galvanising after fabrication is not something we do. If the specification demands a post-weld zinc coating, the panel has to leave our shop for that operation and come back for assembly, and the flatness and thread condition after dipping need to be agreed in advance.
We also do not supply glands, conduits, cable or termination labour. The panel is delivered to the drawing with the entry geometry correct; what goes through the holes is the OEM's scope.
Hazardous-area marking and genset certification belong to the OEM. We fabricate and coat the enclosure to drawing, and we can hold the geometry that a certified assembly needs, but the certificate is not ours to issue.
And if the canopy never leaves a covered plant room, a 1.6 mm plate with round holes and a gasket is adequate. The 3 mm gland plate earns its cost outdoors, on skid-mounted sets, and anywhere the cable drop is long enough to load the gland.
Send the drawing, the cable schedule and the quantity through the genset parts page and the engineering team will confirm plate thickness, cutout tolerance and coating before the quote is issued.
Frequently asked questions
What thickness should a genset cable entry plate be?
2.0 mm CRCA up to M25 glands and 3.0 mm from M32 upward. The gland washer needs a stiff land, and a 1.6 mm plate will bow by 0.5 mm or more across a 200 mm span once the gland is torqued.
Should the gland holes be cut before or after powder coating?
Before. Cut and deburr the hole, then pretreat and coat, masking only the thread land. A hole cut after coating leaves bare steel on the bore and the back face, and rust starts under the film within one monsoon.
What tolerance can you hold on gland cutouts?
±0.2 mm on a laser-cut cutout and ±0.5 mm on the finished panel position. Specify the thread size (M16 to M50) and the cutout as nominal +0.3 mm so the gland washer has a flat land.
Can the panel be supplied in galvanised sheet?
Yes, from IS 277 galvanised sheet at 2.0 mm, cut and powder coated. We do not hot-dip galvanise after fabrication, so any post-weld zinc restoration has to be specified and is outside our scope.
Sources and further reading
- IS 513 — Cold reduced carbon steel sheets and strips (D and DD grades, forming quality) · reviewed 3 Nov 2026
- IEC 60529 — Degrees of protection provided by enclosures (IP code), scope and test conditions · reviewed 3 Nov 2026
- ISO 9227 — Corrosion tests in artificial atmospheres, neutral salt spray test method · reviewed 3 Nov 2026
Send the cable schedule with the drawing
Include gland sizes, cable diameters, the IP rating you need and the coating colour. Our engineering team reviews the entry panel route before quotation.
Request a quote