Custom CNC-Machined High Density Calcium Silicate Parts for a Thailand Customer
A Thailand customer sent us their own drawing for a set of Rumibord T/4720-L14Z insulation components — thick-walled bushings with a blind counterbore pattern, plus a batch of small rectangular blocks. The requirement was clear: 970 kg/m³ high density calcium silicate, CNC machined to the drawing, no chipping on the bore edges, and packed so that nothing arrives broken. Below is how the job was produced.
What was supplied
| Item | Designation | Dimensions |
|---|---|---|
| Calcium silicate bushing | Rumibord T/4720-L14Z | ID 27 × OD 48 × 80 H mm |
| Calcium silicate bushing | Rumibord T/4720-L14Z | ID 26 × OD 48 × 75 H mm |
| Calcium silicate block | High density board, machined | 85 W × 100 L × 30 T mm |
All three items were cut from the same material batch: high density calcium silicate board, bulk density 970 kg/m³, so that thermal behaviour and machining quality stay consistent across the whole shipment.
Material data — 970 kg/m³ grade
| Bulk density | 970 kg/m³ (±10%) |
| Max. service temperature | 1000 °C |
| Compressive strength | ≥ 20 MPa |
| Flexural strength | ≥ 6 MPa |
| Thermal conductivity | approx. 0.18 W/m·K @ 400 °C |
| Permanent linear change | ≤ 0.5 % |
| Composition | Xonotlite / calcium silicate, asbestos free |
The 970 kg/m³ grade is chosen when a part has to carry mechanical load while insulating — flanges, spacers, bushings, die-casting shot sleeve insulation, press platen insulation, induction coil supports. Lower density grades (250–500 kg/m³) insulate better but will not hold a clean machined bore or a tapped feature.
Machining to the customer's drawing
- Blank preparation. High density board is pressed and cured, then cut into blanks with a small machining allowance on every face.
- Turning. OD 48 mm and the through bore (ID 26 / ID 27 mm) are turned in one setup so concentricity is held; typical tolerance is ±0.2 mm on diameters and ±0.3 mm on length.
- Counterbores. The three large blind holes and the small central hole pattern are drilled on a CNC machining centre from the drawing coordinates — depth is controlled so the remaining wall stays sound.
- Edge treatment. Bore mouths are lightly chamfered. Calcium silicate is a mineral board, and a sharp unbroken 90° edge is what chips first in transit.
- Dust control. Machining is done dry with extraction; parts are blown clean so no loose powder travels into the packing.
Inspection and packing
Every piece was checked with calipers and depth gauge against the drawing, and the batch was 100% visually inspected for cracks and edge damage. Parts were then wrapped individually, layered with foam and packed into plywood cases for sea freight to Thailand.
Where these parts are used
- Aluminium die casting — shot sleeve, ladle and holding furnace insulation
- Induction heating — coil spacers and bushings that must not conduct
- Hot press / hot forming tooling — platen insulation blocks
- Glass and non-ferrous metal handling — riser and launder components
- Heat treatment fixtures — load-bearing standoffs inside furnaces
FAQ
Can you machine parts from our drawing only?
Yes. A 2D PDF with tolerances, or a STEP/DWG file, is enough. We confirm density grade, tolerance and machining allowance before cutting.
What tolerance can be held on calcium silicate?
±0.2 mm on turned diameters and ±0.3 mm on lengths is routine on the 970 kg/m³ grade. Tighter tolerances are possible on short features but we prefer to discuss them first — the material is mineral, not metal.
Is the material asbestos free?
Yes. It is a calcium silicate (xonotlite) matrix reinforced with cellulose fibre, asbestos free, with MSDS available.
What is the minimum order?
Small trial batches of machined parts are accepted. Tooling is not required, so quantity mainly affects the unit price, not feasibility.
Which density should I choose?
If the part carries load or needs machined features, use 850–1000 kg/m³. If it only insulates, a lower density grade gives better thermal performance at lower cost.
Ask for a quotation
Send your drawing and we will come back with density grade, tolerance confirmation, unit price and lead time. Email [email protected] or WhatsApp +86 156 8913 8837.