How Much Factory Space for a Block Production Line?

The question of how much factory space for a block production line is settled by adding six zone areas: raw material yard, batching and mixing, forming, curing, the cuber with its stack yard, and the truck apron. Each zone is measured from a figure on the machine sheet: the outer dimensions of the press, the pallet size, the cycle time and the stack size of the cuber.

Our largest press, the QST1800, is 15,500 × 5,500 × 3,200 mm and 34 t of steel. A hall built to that footprint leaves no room for the pallet that leaves the machine every 15 to 25 s, no room for a mould change and no room for the hydraulic power unit. Most plants we are asked to re-plan were built exactly that way.

How is the area of a block line actually calculated?

Start at the machine envelope and work outward. Take the length of the press and add one pallet on the feed side and one on the discharge side, because a pallet has to enter and leave without touching a wall. Add a service face wide enough to pull a mould through. That gives the forming zone, the smallest of the six.

On the QST1500, at 11,500 × 4,550 × 2,800 mm, the forming zone comes out near 14 m by 7 m once a 1,350 mm pallet is added at each end. On the QST8-15, at 9,800 × 3,600 × 2,800 mm, the same method gives about 12 m by 5.5 m. The zone grows with the press, and the press is the cheapest part of the building.

The other four zones do not scale with the press, they scale with output, and output is where the site area runs away.

The pallet is the module for every aisle, bay and yard

Once the pallet is fixed, every horizontal dimension in the plant is a multiple of it. Our lines run 1,400 × 1,400 × 30 mm and 1,350 × 1,150 × 30 mm pallets, and the small line runs 980 × 860 × 22 mm. That figure sets the walkway, the forklift lane and the turning bay.

A walkway one pallet wide takes a man and a hose. A forklift lane is two pallets, so 2.8 m on the 1,400 mm pallet and 2 m on the 980 mm one. A bay where a forklift turns with a cured stack is three pallets, 4.2 m, and that is still a slow turn. Put the three figures on the drawing before you place a machine.

How much of the site does the curing zone take?

Curing decides the site, and its arithmetic is one kind: pallets in cure times pallet area, divided by rack levels, plus aisles. Nothing in that sum comes from the machine brochure.

Pallets in cure follow the cycle. One pallet leaves the press every 15 to 25 s, so at 20 s the line releases about 1,440 pallets in an eight hour shift, whether it is the QST1800 on a 1,400 mm pallet or the QST8-15 on a 980 mm one. A 1,400 mm pallet covers 1.96 m2, a 980 × 860 mm pallet 0.84 m2.

Rack levels divide that deck into floor. A QSDJ line stores each layer on an isolated rack level, and a QSRGY line runs single layer as standard or is built multi-layer to use the height of the building. Four levels cut the floor to a quarter of the deck, which is why a tall shed with a pallet lifter beats a wide one with a forklift. The condition is headroom over the 3,200 mm machine.

Worked example: 90,000 blocks per shift against 220,000 blocks per shift

The small line first. The QST8-15 is rated at 90,000 standard bricks per shift and runs a 980 × 860 mm pallet on a 15 to 23 s cycle. At 20 s it releases 1,440 pallets in a shift, and 1,440 times 0.84 m2 is about 1,210 m2 of deck. Cured single layer that is 1,210 m2 of floor, and 1,815 m2 once a 50 percent aisle allowance is added.

Add the rest. Forming about 65 m2, batching and mixing on a PL Series batcher and a CMP mixer about 120 m2, a covered raw material bay of about 400 m2 for sand, stone and cement, the cuber and its stack yard about 300 m2, and a loading apron about 400 m2. The plant settles near 3,100 m2, and the press accounts for 35 m2 of it.

Now the large line. The QST1800 is rated at 220,000 standard bricks per shift on a 1,400 mm pallet. The same 20 s cycle releases 1,440 pallets at 1.96 m2 each, so one shift of cure is 2,822 m2 of deck. A plant on three shifts holds 4,320 pallets, which is 8,467 m2 of deck; at four rack levels that is 2,117 m2 of floor, about 3,175 m2 with aisles.

Forming 152 m2, batching and mixing 240 m2, a raw material bay of 900 m2, the cuber at 12,000 × 3,000 mm with a 600 m2 stack yard and an 800 m2 loading apron bring the total to roughly 5,900 m2. Output rises 2.4 times and the site less than twice, because the rack bought the difference. Without the rack the same output needs 8,467 m2 of single layer floor.

Which zones are almost always measured too small?

Curing, first. Buyers count the pallets on the machine and forget that a pallet sits in cure while the next one is being filled. Curing deck is the only zone measured in thousands of square metres, and it grows with shifts, not with the press.

The finished goods yard, second. A QS-1200A builds stacks of 1,000 to 1,200 mm square up to 1,400 mm high and cubes about 3,800 pallets in a shift. Each stack needs a forklift lane beside it and a gap to the next row, so the yard holds fewer stacks than the arithmetic suggests. Allow three pallet modules per stack row.

The truck apron, third, and the expensive one to fix later. A 4.2 m turning bay suits a forklift, not a flatbed. A truck that cannot swing round inside the gate reverses onto the road, and the remedy is a wall already built. Reserve the apron while it is still empty ground.

What to settle on the drawing before the floor is poured

Five items decide whether the shed you build fits the line you buy. Each one is a line on the drawing, not a spoken promise.

• Machine envelope with the pallet in and out: press length plus one pallet at each end, and a service face on the hydraulic side wide enough for a mould change.
• Curing deck, calculated from pallets per shift times pallet area, then divided by the rack levels you are actually building.
• Aisle module taken from the pallet: one module for a walkway, two for a forklift lane, three for a turn.
• Cuber and stack yard, sized from the 1,000 to 1,200 mm stack and the 1,400 mm stack height, with lane space between rows.
• Truck apron and gate, reserved before the yard is paved and wide enough for a flatbed to turn in one movement.