1. Problem: Blocks Have Rough or Grainy Surface

✔ Likely Causes

Cavity surface worn or scratched

Dirty mould with dried cement residue

Poor-quality release oil

Over-dry concrete mix

✔ Solutions

Re-polish cavity walls to restore smoothness

Clean mould immediately after each shift

Use proper release agent (avoid diesel)

Increase fine sand proportion or adjust water–cement ratio

Tip: A polished cavity reduces friction and improves block surface finish by up to 30%.

2. Problem: Blocks Stick to the Mould During Demoulding

✔ Likely Causes

Insufficient or uneven release oil

Low-quality release agent

Cavity roughness due to wear

Delay in demoulding or incorrect timing

Overly stiff concrete mix

✔ Solutions

Apply a thin, even layer of professional release oil

Re-polish mould cavities

Keep consistent demoulding time (10–15 seconds post-vibration)

Adjust mix to improve flowability

UNIK MOULD cavity polishing technologies significantly improve demoulding performance.

3. Problem: Block Size Variation Between Cycles

✔ Likely Causes

Mould frame deformation

Loose bolts or misaligned inserts

Machine vibration imbalance

Uneven feeding or inconsistent mix

✔ Solutions

Tighten all bolts using torque wrench

Check alignment pins and replace if worn

Adjust vibration motors for balance

Maintain uniform feeding and mix consistency

Fact: Misalignment as small as 0.5 mm can create visible block size variation.

4. Problem: Cracks or Hairline Fractures on Block Surface

✔ Likely Causes

Mix is too dry

Inadequate curing time

Improper vibration (too low or too high)

Sticking during demoulding

Sudden temperature change after production

✔ Solutions

Increase water or plasticizer

Extend curing to 24–48 hours

Adjust vibration to correct frequency

Ensure smooth demoulding and cavity lubrication

5. Problem: Blocks Have Air Holes or Voids

✔ Likely Causes

Insufficient vibration

Concrete not fully settled in the cavity

Overly viscous mix trapping air

Poor feeding distribution

✔ Solutions

Recalibrate vibration frequency (50–60 Hz)

Improve concrete fluidity

Ensure even and complete feeding

Pre-vibrate before full compaction

Tip: Air voids often indicate the need for higher vibration amplitude.

6. Problem: Uneven Corners or Broken Edges

✔ Likely Causes

Worn or damaged cavity corners

Hard demoulding due to sticky mix

Excessive vibration causing edge fragility

Incorrect curing or drying too fast

✔ Solutions

Repair or replace affected cavity inserts

Apply release oil evenly

Balance vibration to avoid over-compaction

Keep curing conditions stable and shaded

UNIK's reinforced corner designs greatly reduce edge damage.

7. Problem: Mould Deformation or Bending

✔ Likely Causes

Long-term vibration fatigue

Low-quality steel

Incorrect machine–mould matching

Over-tightened bolts or uneven torque

✔ Solutions

Use heat-treated, high-grade steel moulds

Check machine stroke and vibration compatibility

Tighten bolts evenly

Replace frame or inserts if deformation exceeds tolerance

Warning: A bent mould will permanently affect block dimensions.

8. Problem: Noise, Excessive Vibration, or Unstable Mould Movement

✔ Likely Causes

Loose bolts or structural gaps

Deformed mould baseplate

Worn vibration pads

Incorrect installation

✔ Solutions

Tighten or replace bolts

Check baseplate flatness (≤0.05 mm deviation)

Replace rubber vibration pads

Ensure mould is seated correctly on the machine

9. Problem: Inconsistent Block Density

✔ Likely Causes

Uneven vibration distribution

Variable mix ratio

Uneven feeding or filling

Worn mould frame reducing compaction force

✔ Solutions

Balance vibration motors

Standardize mix ratios

Improve feeding uniformity

Replace or rebuild mould frame

Tip: Density variation leads to inconsistent strength - a major quality issue.

10. Problem: Blocks Have Color Variations

✔ Likely Causes

Inconsistent pigment mixing

Dirty mould cavities

Uneven curing environment

Moisture trapped in cavities

✔ Solutions

Pre-mix pigments thoroughly

Clean mould after every batch

Maintain uniform curing temperature

Ensure cavities are completely dry before oiling

Quick Troubleshooting Table

Prevent Problems Before They Happen

Follow these prevention rules:

Clean moulds daily

Re-polish every 10,000–15,000 cycles

Track mould usage with logs or QR/RFID

Standardize vibration settings

Train operators for proper demoulding

Store moulds in dry, covered, clean space

UNIK MOULD supports clients with full maintenance guides, replacement inserts, and professional reconditioning.

Most mould problems are predictable and preventable.

A well-maintained mould can last 80,000–100,000 cycles, maintain perfect block surface quality, and operate smoothly even on high-speed automatic lines.

With proper troubleshooting and UNIK's high-precision mould engineering, you can keep your production line running efficiently with lower defect rates and minimal downtime.

Need support solving mould-related issues in your factory?

👉 Contact UNIK MOULD today for expert troubleshooting, re-polishing service, and machine-matched mould solutions.

Reliable results. Fewer defects. Longer mould life - with UNIK MOULD.