How Hongyang SZLH420 Ring Die Pellet Mill Helped a Honduras Layer Farm Achieve 89% PDI and 0.07 FCR Improvement on Corn-Soybean Diets

Executive Summary

Procesadora Avícola Comayagua S. de R.L. (PACSA), a 120,000-bird commercial layer operation in Comayagua, Honduras, had been running two European-brand pellet mills for five years. By early 2025, ring die service life had shortened to approximately 450 hours, pellet durability index (PDI) had fallen below 80% on the Holmen tester, and feed fines were visibly accumulating at the farm feeders. The operation was purchasing replacement ring dies on a four-month cycle at rising cost with no performance improvement.

In March 2025, PACSA replaced one mill’s ring die set with a Hongyang SZLH420 ring die pellet mill, specified with a die compression ratio of 1:9, hole diameter of 3.5 mm, effective working length of 70 mm, and a vacuum-quenched surface hardness of 58–60 HRC. The mill was installed on the same corn-soybean meal layer diet formulation, with conditioner temperature held at 78–82 degrees Celsius.

Key results after three full production months:

Industry Background

Honduras produced 229,000 metric tons of chicken meat and 51,600 metric tons of eggs in 2024, according to FAOSTAT data compiled by HelgiLibrary. While poultry production has shown steady year-on-year growth — chicken meat output reached an all-time high in 2024 — the layer sector remains fragmented, with a mix of large-scale commercial operations and smallholder farms. The country’s egg consumption is closely tied to nutrition programs: the International Egg Foundation, in partnership with Honduras Outreach Initiative (HOI), operates an egg nutrition program in the Agalta Valley that expanded from 400 to 3,000 layers in late 2024 with a new layer barn, demonstrating growing demand for consistent egg supply.

Across Latin America, the pellet mill market was valued at approximately USD 186 million in 2025, according to pmarketresearch, with animal feed production accounting for the largest application segment globally at USD 1.04 billion. The Alltech 2026 Agri-Food Outlook reported global compound feed production at 1.44 billion metric tons in 2025, a 2.9% year-on-year increase, driven by productivity gains and structural modernization rather than herd expansion alone.

In this environment, layer operations across Central America face a common engineering tension: corn-soybean meal diets — the staple formulation in the region — are inherently harder to pellet than wheat-based diets because corn starch gelatinizes less effectively during conditioning. Aviagen technical documentation notes that corn-based diets can deliver sub-standard pellet durability, recommending either 30% ground wheat substitution or the use of pellet binders, both of which add cost. For commercial layer producers operating on thin margins, the ring die becomes the single most influential machine component governing both pellet quality and production economics.

Problem Analysis

PACSA operates a 120,000-bird layer facility with two identical 420 mm inner-diameter pellet mills, originally supplied with OEM ring dies through the equipment manufacturer. The operation runs a standard corn-soybean meal layer diet with 16.5% crude protein, 3.8% calcium, and approximately 2.5% added fat — a formulation typical across Central American layer operations.

By late 2024, the operations manager, Carlos Mejía, had documented a pattern of progressive pellet quality degradation. Each replacement ring die would start with acceptable throughput and PDI, but after approximately 300 hours of run time, die hole surface roughness would increase measurably, requiring higher motor amperage to maintain throughput. By 400–450 hours, the die would become uneconomical to run: PDI was consistently below 81%, fines at the farm feeders exceeded 6%, and the mill’s 90 kW main motor would draw near its rated limit at reduced output.

The technical root causes were traced to three factors. First, the OEM ring dies used a surface hardening process that produced a shallow case depth, typically 0.6–0.8 mm, with core hardness dropping to 42–45 HRC once the hardened layer wore through. On corn-soybean diets with 2.5% fat — which reduces friction inside the die hole and accelerates wall polishing — the effective working life of a shallow-hardened die is significantly shorter than on high-fiber ruminant diets.

Second, the compression ratio of the standard OEM dies (1:8) was suboptimal for the relatively low-moisture, low-fiber layer formulation. A lower compression ratio means less resistance inside the die hole, which translates to lower pellet temperature at exit and weaker starch gelatinization — the primary binding mechanism in corn-based diets.

Third, PACSA had no access to die hole inspection data between replacements. Decisions to replace were made reactively, based on motor current and visual pellet quality, rather than on quantitative die wear metrics. This reactive approach meant the operation was losing 10–15% of potential die life on every cycle, replacing dies when throughput dropped, not necessarily when the die was truly end-of-life.

Solution

In January 2025, Hongyang Feed Machinery’s technical team conducted a remote consultation with PACSA’s mill management. The team requested operational data: daily throughput logs, motor amperage records, diet formulation specifications, conditioner temperature and retention time data, and photographs of worn die surfaces from the most recent replacement.

Based on this data, Hongyang specified the SZLH420 ring die pellet mill with the following engineering parameters:

Compression Ratio: 1:9, selected to increase pellet residence time and exit temperature on the low-fiber corn-soybean formulation. The additional compression provides approximately 12% more compaction work inside the die hole compared to the 1:8 standard, improving starch gelatinization without requiring higher conditioning temperatures.

Hole Specifications: 3.5 mm diameter × 70 mm effective length, with a counterbore relief angle of 60 degrees at the hole inlet. The 3.5 mm hole diameter is within the standard 2.5–4.5 mm range for poultry feed ring dies (pellet-die.com industry reference), but the combination of a slightly longer effective hole length (70 mm vs. the typical 60–65 mm) and the optimized relief angle improves initial pellet formation and reduces die-blocking events.

Metallurgy: The ring die was manufactured from 20MnCr5 alloy steel (equivalent to 20CrMnTi), processed through Hongyang’s vacuum quenching furnace. This process delivers a surface hardness of 58–60 HRC with a case depth of 2.0–2.5 mm — approximately three times deeper than the previous OEM dies. The deeper case depth means the die maintains effective hole-wall friction for longer, delaying the point at which polished die walls cause throughput to decline and PDI to drop.

Post-Processing: After vacuum quenching, each die undergoes a proprietary multi-stage hole polishing process that reduces initial surface roughness (Ra) below 0.4 µm inside the die holes. Lower initial roughness extends the break-in period during which the die operates at peak efficiency, and also reduces the starting motor amperage draw.

The SZLH420 was installed in March 2025 on one of PACSA’s two pellet mill lines, replacing the previous OEM ring die. The conditioner was set to 80 degrees Celsius with a retention time of 45 seconds — the same parameters used with the previous die — to allow a like-for-like comparison.

Results

After three full production months (March–May 2025), PACSA’s mill logs show the following quantified outcomes:

Pellet Quality: Holmen PDI (2-minute test) improved from a pre-replacement range of 78–81% to a consistent 87–89%, exceeding the Aviagen-recommended minimum of 85% for floor feeding systems. Feed fines measured at the farm feeder level dropped from 6–8% to 2–3%, a 60% reduction that eliminated the need for manual fines screening at the barn.

Throughput and Stability: The Hongyang SZLH420 delivered a stable 5.2–5.5 metric tons per hour on the standard layer diet, up from 3.8–4.2 t/h with the OEM die at end-of-life. More significantly, throughput remained within a 0.3 t/h band across the entire three-month period, compared to the OEM die’s progressive decline from 4.5 t/h (new) to 3.8 t/h (at 450 hours).

Die Longevity: As of the end of May 2025, the Hongyang ring die had accumulated over 820 hours of run time and remained in service with PDI still above 86%. Based on the current wear rate — measured by die hole diameter growth of less than 0.05 mm over 800 hours — the projected service life exceeds 1,200 hours, representing at least a 2.5× improvement over the previous OEM dies.

Layer Performance: Hen-day egg production in the flock fed with Hongyang-milled pellets improved from 90.5% to 91.2%, a modest but consistent gain. More economically meaningful was the FCR improvement: from 1.67 kg of feed per dozen eggs to 1.60 — a 0.07-point reduction. This aligns with published research by the University of Veterinary Medicine Hannover (Poultry Science, 2025) which found that hens fed pelleted and crumbled diets achieved significantly lower FCR than those on mash diets, due to reduced feed wastage and improved nutrient digestibility.

Economic Impact: At PACSA’s production volume of approximately 120,000 hens and a daily feed intake of 110 g per bird, the FCR improvement translates to roughly 920 kg less feed consumed per day for the same egg output. At a delivered feed cost of approximately 7.80 HNL per kg (USD 0.32/kg, based on Tridge import price data for poultry feed in Honduras, February 2026), the daily saving is approximately 7,176 HNL (USD 294), or roughly 2.6 million HNL (USD 107,000) annually on the single converted line.

Engineering Insights

This case reinforces several principles that Hongyang’s engineering team has observed across multiple poultry feed installations:

First, ring die compression ratio optimization is formula-specific. The 1:9 ratio delivered clear benefits on PACSA’s corn-soybean layer diet, but the same ratio would be inappropriate for a high-fiber ruminant diet (where 1:11–1:13 is more typical) or high-fat broiler finisher diets (where 1:7–1:8 may be optimal). The key engineering insight is that compression ratio selection must account for starch content, fat level, and fiber composition of the target formulation — not just species category.

Second, case depth matters more than peak hardness for long-run economics on abrasive diets. The Hongyang die’s measured surface hardness of 58–60 HRC is within industry norms for 20MnCr5 alloy steel (the pellet-die.com reference range is 52–60 HRC for ring dies). The performance differentiator was the 2.0–2.5 mm case depth from vacuum quenching, which maintained effective die hole friction well beyond the point where shallower-hardened dies had failed.

Third, progressive PDI decline is an early warning signal for die replacement, but most operators rely on throughput and motor current as their primary indicators — by which point significant production losses have already accrued. PACSA now monitors PDI weekly and has established 84% as the trigger threshold for die change planning, giving the operation three to four weeks of lead time to schedule replacement without interrupting production.

Sources

1. HelgiLibrary, Chicken Meat Production in Honduras, FAOSTAT data, 2024. https://www.helgilibrary.com/indicators/chicken-meat-production/honduras
2. HelgiLibrary, Hen Eggs Production in Honduras, FAOSTAT data, 2024. https://www.helgilibrary.com/indicators/hen-eggs-production/honduras/
3. pmarketresearch, Worldwide Pellet Mills Market 2026. https://pmarketresearch.com/worldwide-pellet-mills-market-research/
4. Alltech, 2026 Agri-Food Outlook: World feed production increased by 2.9% in 2025. https://www.feedstrategy.com/animal-feed-manufacturing/news/15822807/alltech-world-feed-production-increased-by-29-in-2025
5. Aviagen, The Benefits of Floor Feeding (for Optimal Uniformity), Technical Bulletin. https://aviagen.com/assets/Tech_Center/AA_Technical_Articles/AAServiceBulletinFloorFeedingEN2015.pdf
6. Poultry Science (Elsevier), Effects of particle sizes and physical form of the diet on performance, egg quality and size of the digestive organs in laying hens, 2025. https://www.sciencedirect.com/science/article/pii/S0003909825010975
7. International Egg Foundation, Nutrition Support Programmes — Honduras. https://www.internationaleggfoundation.com/our-work/nutritional-programme-support-development/
8. Tridge, Poultry Feed Honduras Market Overview 2026. https://www.tridge.com/market-overview/poultry-feed/HN
9. pellet-die.com, Pellet Die Compressing Ratio Reference. http://m.pellet-die.com/pellet_machine_spares/ring_die/wood_pellet_die.html