QST8-15 Block Making Machine: 14 t, 45 kW, 90,000 Bricks a Shift

A QST8-15 block making machine is the first automatic press many factories buy. It runs on 44.9 kW of installed power and weighs 14 t, so it is small enough for one bay yet built to hold a full automatic cycle. Its footprint is 9,800 × 3,600 × 2,800 mm. If you are stepping up from a manual or semi automatic press, this is the machine where the mould, the pallet and the hydraulic system start working to a timer instead of to an operator's hand. Below we go through each number a buyer should check before signing.

1. What 44.9 kW and 14 t tell you about this machine

Power and mass decide what a machine can do all day. A 44.9 kW drive on a 14 t frame means the vibration unit and the hydraulic pump are sized for continuous production, not for a few hours of light work. Our forming method is vibration plus press moulding, with a vibration frequency of 3,800 to 4,500 cycles per minute. A 14 t frame absorbs that force without creeping across the floor.

The footprint is 9,800 × 3,600 × 2,800 mm. That is compact for an automatic line, and it is the main reason this model fits workshops where a larger machine would not go in.

Set beside the QT5-15 and the QST6-15, this model carries a heavier frame, a wider pallet and a higher working pressure. The extra steel is not decoration. It is what holds the mould closed while 95 kN of vibration passes through the mix, cycle after cycle, for a full shift.

2. Why 31.5 MPa at 95 kN saves cement

Hydraulic pressure sets how hard the mix is squeezed before the block leaves the mould. The QST8-15 presses at 31.5 MPa with 95 kN of vibration force. The QT5-15 and the QST6-15 press at 25 MPa. That gap is a density gap.

Every 1% of air left inside the mix costs about 5% of compressive strength. Most factories pay for that air with about 30 kg of extra cement per cubic metre. A press that closes the mix at 31.5 MPa pushes the air out before curing starts, so you reach the tested strength with less binder in the recipe.

A density of 1,850 kg/m³ is the usual working target for a 7 MPa class block. Reaching it is a pressing and vibration job. Adding cement to a mix that was never compacted properly only raises the bill.

3. Pallet 980 × 860 × 22 mm and the 15 to 23 s cycle

The pallet on this model is 980 × 860 × 22 mm, and the cycle runs 15 to 23 s depending on the product. On solid bricks the machine reaches up to 90,000 bricks in an 8 hour shift.

The pallet is 22 mm thick here, against 20 mm on the QT5-15 and the QST6-15. Steel that keeps its flatness under 95 kN holds block height steady from the first pallet of the shift to the last.

Treat the output figure as a shift number, not a peak number. It assumes the pallet circuit, the curing area and the raw material feed all hold pace with the press. When a supplier quotes a higher output, ask which product and which cycle time were used, and ask for the pallet size behind the number.

Cycle time describes what happens inside the machine. Strength arrives days later, from hydration, and it follows the temperature and moisture of the curing area rather than the press. Keep the water to cement ratio inside the 0.35 to 0.45 band, because extra water lifts the cement bill and lowers the tested strength at the same time.

4. Power supply, starting current and the 10 × 4 m bay

Plan the site for about 45 kW of supply. The installed power is 44.9 kW, and the two figures sit close together on purpose. Nothing on this machine is meant to run on a smaller feed.

An induction motor pulls 5 to 7 times its rated current in the moment it starts. A 15 to 20 s cycle means the vibration motors start and stop more than 140 times every hour. Your cable, breaker and transformer have to carry those peaks, not only the running load. Send us the voltage you have on site and we size the panel to match it.

The machine itself needs a bay of about 10 × 4 m, plus space for the pallet stack and the curing area. Pour a level foundation and anchor the frame down; a 14 t machine that walks on its bolts will not hold cycle time.

5. Crew size and mould change

A typical QST8-15 line runs with 4 to 6 people per shift:

• One operator at the control panel, watching cycle time and block height.
• One or two people moving pallets and green blocks away from the machine.
• One person on the mixer and the batching feed.
• One person on quality checks and mould changes.

6. When the QST1200 is the better buy

The QST1200 runs at 57.6 kW, presses 63 bricks per mould and reaches up to 120,960 bricks in an 8 hour shift. It is the right step when your order book is already larger than one QST8-15 can serve, or when your block design needs a pallet wider than 980 mm.

The stacker on this line is a 3.0 kW unit, while our larger models use a 3.7 kW stacker. It lifts green blocks off the pallet without cracking the corners, which matters more on hollow blocks than on solid bricks.

Stay with the QST8-15 when the building is small, the supply is close to 45 kW and the crew is 4 to 6 people. A QS stacking system on the same line cuts the palletising step to one person. The table below puts four models side by side on the numbers that matter at order time.

7. Moulds, pallets and what to send us

Two items decide how fast a new line settles down: the mould and the pallet stock. A standard mould ships with the machine and fits a frame that is already drilled for it. A custom product needs a new mould built first, so order it early. On pallets, buy stock in step with the curing area you plan to run, because a press that outruns its pallets stops as surely as one that runs out of mix.

Send us four things before you ask for a quotation: the block and paver sizes you will sell, the output you need per shift, the voltage available on your site, and your destination plus unloading conditions. We size the press, the mould, the pallet count and the stacking system around those answers.