Interlocking Blocks for Reconstruction Projects in Syria: Moulds and Output

Interlocking blocks for reconstruction projects in Syria are chosen on the mould, not on the machine frame. A dry-stacked wall stands only because every block leaves the cavity at the same size and with its edges intact, so the tongue, the groove and the release taper matter more than the tonnage of the press behind them. On a QST6-15 the moulding cycle runs 15 to 23 seconds under 68 kN of excitation force and 25 MPa of rated pressure.

What decides whether a dry-stacked wall holds?

A dry-stacked interlocking wall carries load through contact faces rather than mortar, so one oversize block lifts the whole course and one undersize block leaves a rocking gap. Two mould properties govern that. The first is dimensional tolerance, cavity to cavity and mould set to mould set, held at micron level on a machined mould by CNC work on the frame, the core, the base plate and the guiding assembly. The second is edge retention: the tongue and the groove have to stay sharp and square through thousands of pressing strokes, which is why wear-resistant alloy steel and a controlled hardening cycle count for more than the price of the mould.

Tolerance is a property of the mould, not of the press. Vibration and tonnage fix density, but they cannot correct a cavity cut outside its size, and a mould that has lost its edges shows up in the yard as chipped corners and density swings across the pallet.

How do cavities per mould convert into shift output?

Output is cavities multiplied by strokes. An 8-hour shift holds 28,800 seconds, so a moulding cycle of 18 to 22 seconds allows roughly 1,300 to 1,600 strokes, and the cavities in your block set the ceiling of that tier. The same press body carries very different cavity counts: a 390 × 190 × 190 mm hollow block runs 5 pieces per mould on a QS800, 10 on a QS1000 and 12 on a QS1500, while a 240 × 115 × 51 mm standard brick runs 28, 45 and 87 pieces on the same three frames.

A published output figure sits on the same arithmetic. A QST6-15 returns 6 hollow blocks of 390 × 190 × 190 mm per mould and 8,640 to 11,520 pieces in an 8-hour shift at a 15 to 23 second cycle. Cavity count is the part you can still change at order stage; cycle time is fixed by the machine already bought.

• QS800: 5 hollow blocks of 390 × 190 × 190 mm, 28 standard bricks of 240 × 115 × 51 mm, moulding area 1,100 × 680 mm.
• QS1000: 10 hollow blocks, 45 standard bricks, moulding area 1,100 × 850 mm.
• QS1500: 12 hollow blocks, 87 standard bricks, moulding area 1,440 × 850 mm.
• All three press from both directions in an 18 to 22 second cycle at 31.5 MPa of working pressure.

Why does taper decide whether a green block strips cleanly?

The mould has to let the block go without dragging it. Every side wall of an interlocking cavity and every nose of the tongue is cut with a slight release taper so the block clears the cavity as the mould lifts. Too little taper and the green block rubs the cavity wall on the way out, the corner crumbles and the sharp arris the wall leans on is gone. Too much taper and the block drops out freely, but the interlock sits loose, so the dry joint loses bearing area.

Stripping also depends on what the block stands on. A pallet that is not flat, or whose thickness varies across the board, tilts the mould over the last millimetres of the stroke. On a pallet-fed line the pallet is a tool, not a board: a QST6-15 runs a 980 × 680 × 20 mm pallet and a QST8-15 a 980 × 860 × 22 mm pallet, and the tolerance on both transfers into the block.

How does compaction density set the stacking height?

Density decides whether a green block can be stacked or has to be nursed. A block that leaves the mould hard and sharp-edged can be turned and stacked straight away; a soft one stays on its pallet until it stiffens, and the pallet fleet grows with every extra hour in curing. Pallet-free wet cubing works on that principle: the fresh block is stacked straight off the mould to a cubing height of 1,100 mm, about 10 layers of standard brick.

Stack height then follows the evenness of the density through the block. A press that compacts from one side leaves a gradient between the pressed face and the far face, and the lighter end limits the stack before the bottom layers deform. Pressing from both ends in one 18 to 22 second cycle flattens that gradient, which is why sharper edges and consistent strength appear together in one specification.

• QS-1000G-A fixed cuber: stacking height up to 1,300 mm, clamping weight 500 kg, minimum clamped thickness above 50 mm.
• QS-1000G-B and QS-1000G-C: maximum cuber height 1,400 mm, at 15 to 18 seconds and 12 to 15 seconds per layer.
• QS-1000Y mobile cuber: up to 20 layers of standard solid brick or 11 layers of hollow block in one pass, walking at about 2 km/h.

How should mould life be counted in the budget?

A mould is a consumable, and it should be budgeted that way. The honest way to compare two mould offers is cost divided by the number of blocks that mould will produce before its cavity dimensions drift outside the tolerance the wall needs. The figure to give a supplier is therefore the total block count you intend to mould, not the number of machines you are buying, and alloy steel, CNC machining at micron level and a controlled hardening cycle are the three inputs that push that count up.

Buy cavity sets against the block count, not against the machine count. A yard that will mould one product for years is served better by a heavier cavity set than by a second spare mould of the same grade, and a yard that changes product every few weeks needs the opposite. Note also which parts wear as one set: the mould frame, the core, the base plate, the guiding assembly and the positioning mechanism.

Which mould and pallet set suits a hand-led semi-automatic yard?

Where the machine is automatic but everything downstream of the mould is done by hand, the pallet count is the real constraint. One pallet leaves the machine loaded with green blocks and the next stroke needs an empty one, so the fleet is set by the cycle time plus the hours the blocks need before they can be turned out. On a QST6-15 that is a fleet of 980 × 680 × 20 mm pallets sized to the shift, fed by a machine drawing 34.4 kW at the panel.

Three purchases decide whether a hand-led yard keeps pace with the machine: an automatic pallet feeder on a 13 second feeding cycle, a pallet-free handling route that removes the boards altogether, and a forklift clamp that lifts 500 to 800 standard bricks or 40 hollow blocks per bite. Order the extra cavity sets before the extra handling, because a mould change you cannot make is a shift you lose.