The steel grade of your tablet dies and punches directly affects tooling life, tablet quality, and production costs. Different formulations require different steel properties — abrasive powders need harder steel, while corrosive formulations need corrosion-resistant grades.
EMMKAY INDUSTRIES manufactures tablet dies and punches in four steel grades, each designed for specific production requirements.
Steel Grade Comparison
| Grade | Hardness | Wear | Toughness | Corrosion | Cost |
|---|---|---|---|---|---|
| EMMKAY Special | 55-60 HRC | Good | Good | Excellent | Most affordable |
| HCHC (D3) | 62-64 HRC | Excellent | Lower | Good | Moderate |
| OHNS | 58-62 HRC | Good | Good | Moderate | Moderate |
| S7 | 56-58 HRC | Moderate | Excellent | Moderate | Similar to HCHC |
OHNS — Standard Steel (Most Common)
Oil Hardening Non-Shrinking steel. Hardness: 58-62 HRC. The default choice for approximately 70% of tablet manufacturing applications.
When to choose OHNS:
- ·Standard pharmaceutical tablets (paracetamol, ibuprofen, metformin)
- ·Nutraceutical tablets (herbal extracts, basic vitamins)
- ·Ayurvedic formulations
- ·When cost-effectiveness is a priority
HCHC (D3) — Standard for Dies
High Carbon High Chromium steel (D3 tool steel). Hardness: 62-64 HRC. The standard recommendation for all die bores due to superior wear resistance — dies experience more abrasion than punches.
When to choose HCHC:
- ·All die bores — standard recommendation for dies
- ·Abrasive formulations (calcium, iron, minerals) — for both dies and punches
- ·Mineral-based nutraceutical tablets
- ·When maximum tooling life is the priority
S7 — Impact-Resistant Steel
Shock-resistant tool steel. Hardness: 56-58 HRC. Highest impact resistance of any grade — absorbs energy better than OHNS or HCHC.
When to choose S7:
- ·Deep concave or cup-shaped tablet designs
- ·Formulations that cause punch tip chipping
- ·High compression force applications
- ·Large tablets (20mm+) with thin walls
EMMKAY Special Steel — Corrosion-Resistant
Proprietary corrosion-resistant tool steel. Hardness: 55-60 HRC. Developed specifically for the challenges of corrosive formulations.
When to choose EMMKAY Special Steel:
- ·Manufacturing environments with high humidity
- ·When rust and pitting are recurring problems on standard tooling
- ·Budget-conscious manufacturers looking for the most affordable option
Quick Selection Guide
| Your Situation | Recommended | Why |
|---|---|---|
| Standard pharma tablets | OHNS | Good all-round for punches |
| Dies (all formulations) | HCHC (D3) | Standard recommendation for dies |
| Calcium or mineral tablets | HCHC (D3) | Hardest — resists abrasive wear |
| Iron supplement tablets | HCHC (D3) | Maximum wear resistance |
| Deep concave designs | S7 | Impact-resistant, prevents chipping |
| Punch tips keep chipping | S7 | Absorbs impact energy |
| Effervescent tablets | S7 or HCHC | Toughness or wear resistance |
| Vitamin C tablets | HCHC (D3) | Resists acid and abrasion |
| High humidity factory | EMMKAY Special | Prevents rust and pitting |
| Budget-conscious | EMMKAY Special | Most affordable option |
How to Choose the Right Steel Grade for Your Formulation
Selecting the correct steel grade depends on the physical and chemical properties of your tablet formulation. Abrasive ingredients wear tooling faster, corrosive ingredients cause pitting and rust, and high-impact tablet designs stress punch tips. Use the guide below to match your formulation type to the optimal steel grade.
Standard Formulations
Examples: Paracetamol, metformin, ibuprofen, common antibiotics, herbal extracts
Recommendation: OHNS punches + HCHC dies
This is the most cost-effective combination for the majority of pharmaceutical and ayurvedic tablets. OHNS provides good hardness and toughness for punches, while HCHC in the die bore handles the higher abrasion from powder flow through the bore.
Abrasive Formulations
Examples: Calcium carbonate, iron oxide, mineral supplements, calcium phosphate
Recommendation: HCHC for both punches and dies — consider TiN coating
Abrasive powders accelerate wear on both the die bore and punch tip faces. HCHC (D3) at 62-64 HRC provides the highest wear resistance. For extremely abrasive formulations, adding a TiN (Titanium Nitride) coating can extend tooling life by an additional 30-50%.
Corrosive / Acidic Formulations
Examples: Effervescent tablets, vitamin C, citric acid blends, ascorbic acid
Recommendation: EMMKAY Special Steel or S7 with CrN coating
Acidic ingredients cause pitting and corrosion on standard tool steels. EMMKAY Special Steel offers built-in corrosion resistance at an affordable price. For higher-volume production, S7 steel with a CrN (Chromium Nitride) coating provides both toughness and a corrosion-resistant surface barrier.
High-Impact Formulations
Examples: Deep concave tablets, large tablets (20mm+), cup-shaped designs, chipping-prone profiles
Recommendation: S7 steel for punches, HCHC for dies
Tablet designs with deep concavity or thin edges concentrate compression force on small areas of the punch tip, leading to chipping and fracture. S7 steel absorbs impact energy far better than OHNS or HCHC, preventing premature tip failure. Pair S7 punches with HCHC dies for the best combination of impact resistance and bore wear life.
Formulation-to-Steel Recommendation Summary
| Formulation Type | Recommended Steel | Expected Lifespan |
|---|---|---|
| Standard pharma (paracetamol, metformin) | OHNS punches + HCHC dies | 3–8M tablets |
| Abrasive (calcium, iron, minerals) | HCHC punches + HCHC dies | 5–10M tablets |
| Corrosive / acidic (effervescent, vitamin C) | EMMKAY Special or S7 + CrN | 4–8M tablets |
| High-impact (deep concave, large tablets) | S7 punches + HCHC dies | 4–7M tablets |
| Budget-conscious / humid environment | EMMKAY Special Steel | 4–8M tablets |
Steel Grade Cost vs Lifespan Analysis
Choosing the cheapest steel grade does not always mean the lowest production cost. A more expensive grade that lasts twice as long will reduce your cost per million tablets and minimize press downtime for tooling changeovers. The table below compares the approximate cost premium, expected lifespan, and cost efficiency of each grade.
| Steel Grade | Approx. Cost Premium | Expected Lifespan | Cost per Million Tablets | Best Value For |
|---|---|---|---|---|
| OHNS | Baseline | 3–5M tablets | ₹300–500 | Standard formulations |
| HCHC (D3) | +20–30% | 5–10M tablets | ₹200–350 | Abrasive formulations |
| S7 | +30–40% | 4–7M tablets | ₹250–400 | Impact-prone designs |
| EMMKAY Special | +15–25% | 4–8M tablets | ₹200–350 | Corrosive formulations |
Note: Lifespan figures are approximate and depend on formulation abrasiveness, compression force, press speed, and maintenance practices. Actual results may vary. Contact EMMKAY INDUSTRIES for a recommendation based on your specific formulation and production volume.
Frequently Asked Questions
Can I mix steel grades in the same turret?
No. All dies and punches on a turret should be the same steel grade and hardness to ensure uniform compression and consistent tablet quality.
How much longer does HCHC last compared to OHNS?
For abrasive formulations, HCHC typically lasts 30-50% longer than OHNS. For non-abrasive formulations, the difference is smaller and OHNS is usually the better value. Read our tooling lifespan guide.
Is EMMKAY Special Steel available for all shapes?
Yes. All four steel grades are available for every tablet shape — round, capsule, oval, custom designs, and multi-tip.
Can I use different steel grades for punches and dies?
Yes, this is common practice. Most manufacturers use HCHC for dies (higher wear resistance needed for the bore) and OHNS for punches (good balance of hardness and toughness). For abrasive formulations, upgrade both to HCHC. This mixed approach gives you the best balance of performance and cost.
What hardness should I specify for my tooling?
Hardness is determined by the steel grade and heat treatment. OHNS: 58-62 HRC, HCHC: 62-64 HRC, S7: 54-58 HRC. Higher hardness means better wear resistance but lower toughness. EMMKAY heat-treats all tooling to the optimal range for each grade — you do not need to specify hardness separately.