KBr Pellet Die
The die holds the powder, defines the pellet diameter and transfers the press load to the sample. For transmission FTIR the standard format is a 13 mm KBr pellet; for other applications Hench supplies circular, cylindrical, square, split and specialty dies.
13 mm KBr Pellet Dies
The most common FTIR format is a 13 mm disc. Hench supplies the HM-12 13 mm demoulding die for standard pellets and the HM-2 no-demould die where the pellet is measured in place.
Circular and Cylindrical Dies
Larger pellets use the HMY circular die (2.0–40.9 mm), the HMY round sample die (41–80 mm) and the HMY cylindrical die (81–200 mm).
Square and Rectangular Dies
Square and rectangular formats are used for XRF pellets and for samples that must match a rectangular holder: the HMF square die (41–80 mm), the HMF rectangular die (81–200 mm) and the HMF square die (3–40 mm).
Split, Ring and Specialty Dies
Where demoulding is difficult, split dies allow the pellet to be released without damage: the HMK-F square split die and the HMK-Y circular valve pressing die. Other formats include the HMO ring-shaped die, the HMQ spherical die, the HMD polygon die, the HMT special-shaped die, the HML anti-cracking die, the HMS circular bidirectional die and the HMW sintered carbide die for hard powders.
How to Choose a Pellet Die
- FTIR transmission: 13 mm die with a polished surface, used with KBr powder.
- XRF pressed pellets: 32 mm and 40 mm formats, including borate and steel-ring dies.
- Hard or abrasive powders: carbide dies to limit wear.
- Fragile pellets: split or anti-cracking dies that reduce demoulding stress.
- Non-standard shapes: polygon, spherical or special-shaped dies.
The pellet molding die series collects the full range, and the KBr pellet press page covers the press side.
Frequently Asked Questions
Die Selection by Diameter and Format
| Die | Diameter | Typical use |
|---|---|---|
| HM-12 13 mm demoulding die | 13 mm | Standard FTIR transmission pellets |
| HMY circular die (2.0–40.9 mm) | 2.0–40.9 mm | Small round pellets |
| HMY round sample die (41–80 mm) | 41–80 mm | Larger round pellets |
| HMY cylindrical die (81–200 mm) | 81–200 mm | Large cylindrical formats |
| HMF square die (3–40 mm) | 3–40 mm | Small square pellets |
| HMK-F square split die | split type | Pellets that are hard to demould |
Method Notes for Pellet Dies
For a reproducible pellet the die has to match three things: the target diameter, the press adapter and the sample holder. For routine work we document a 13 mm die, 8-10 tons of load, a hold of 60-90 seconds and a 1-2 minute vacuum step before pressing. The complete sequence is published in our KBr pellet SOP.
Keep the die clean and dry between samples, and release the pressure slowly: moisture and a fast release are the usual causes of cloudy or cracked pellets. Demoulding dies use a separate base or sleeve so the pellet can be pushed out without tilting, while split and anti-cracking dies are used for fragile samples or for pellets that tend to stick.
Which die size is standard for FTIR?
13 mm is the most widely used diameter for KBr pellets, matching common pellet holders.
What is a demoulding die?
It is a die with a separate base or sleeve that allows the finished pellet to be pushed out without tilting it.
Do I need a different die for XRF?
XRF pellets are usually larger, in the 32–40 mm range, and often use a borate or steel-ring die. See the XRF sample preparation page.
Need help choosing the right configuration? Request a quote and include your sample type, required pellet or die size and the press you are using.