Executive Summary
Spain is not only the European Union’s largest pig producer but also its top compound feed manufacturer-generating 38.8 million tons of compound feed in 2024, of which pig feed accounted for 46.87%, or roughly 18.2 million tons. Within this high-volume, quality-sensitive landscape, a mid-scale swine feed mill in the Aragon region sought to replace an aging pelleting line that was producing inconsistent pellet durability and struggling with throughput stability. The mill selected Hongyang Feed Machinery’s SZLH420 ring die pellet mill paired with custom-engineered HYPM ring dies. Eighteen months into operation, the line has delivered a pellet durability index (PDI) consistently above 92%, a grower-feed throughput of 9-10 tons per hour (TPH), and documented improvements in downstream feed conversion on partner pig farms. This case illustrates how ring die engineering, correct compression ratio matching, and responsive after-sales support can yield measurable results in a mature, competitive European feed market.
1. Context: Spain’s Swine Feed Industry at a Glance
Understanding why this upgrade mattered requires a brief look at Spain’s position in global pig and feed production. According to the Spanish Ministry of Agriculture, Fisheries and Food (MAPA), Spain slaughtered 53.88 million pigs in 2024-a 1.5% year-on-year increase-with Catalonia (22.4 million head), Aragon (11.3 million head), and Castile and Leon (6.2 million head) collectively accounting for over 72% of national throughput. Spain is also the world’s second-largest pork exporter behind the United States, shipping 687,000 tons in Q1 2025 alone.
On the feed side, Spain’s 38.8-million-ton compound feed output in 2024 represented a 1.5% increase over 2023, against an EU-wide contraction of 0.4% (European Feed Manufacturers’ Federation data). Pig feed remains the dominant segment, and within Aragon-home to approximately 4,618 pig farms-feed mills operate under relentless pressure to deliver consistent pellet quality, as any variation in durability or nutrient homogeneity directly affects the feed conversion ratios (FCR) that determine farm profitability.
2. The Challenge: Aging Pelleting Equipment and Inconsistent PDI
The feed mill in question-a family-operated business producing approximately 60,000 tons of swine feed annually, primarily for grower and finisher pig stages-was running a pelleting line that had been in service for over 12 years. Three specific problems had emerged:
Declining pellet durability. The Pellet Durability Index (PDI), a standard measure of how well pellets withstand handling and transport before reaching the animal, had fallen to the 86-88% range for the mill’s standard 3.5 mm grower-feed pellets. Industry consensus considers 92% the optimal PDI threshold; below this, excessive fines generation during pneumatic conveying and truck loading becomes a measurable economic loss. Research published by Metalteco and other equipment manufacturers confirms that each percentage point of PDI lost typically translates to fines that represent both wasted raw material and reduced voluntary feed intake at the farm.
Throughput instability. Output fluctuated between 6 and 9 TPH depending on raw-material moisture and batch formulation, making production scheduling unreliable. This was partly a motor-load issue and partly a consequence of worn ring die holes that were no longer maintaining their designed compression ratio.
Rising energy costs. With Spain’s industrial electricity prices among the highest in Southern Europe, the mill’s specific energy consumption-measured in kWh per ton of pelleted feed-had crept upward as the old die required higher motor loads to push material through partially deformed holes.
The mill manager set three objectives for any new pelleting line: PDI >= 92% on standard swine grower formulations; stable throughput >= 8 TPH across all swine feed batches; and total cost of ownership (TCO) that would break even within 24 months against the old line’s rising maintenance and energy costs.
3. Equipment Selection and Technical Configuration
After evaluating proposals from three suppliers, the mill chose Hongyang Feed Machinery’s SZLH420 ring die pellet mill, paired with HYPM-series ring dies manufactured from high-chromium alloy steel (equivalent to 420SS grade, surface hardness 58-62 HRC after vacuum heat treatment).
Ring die compression ratio selection. For swine grower feed formulations-typically containing 60-65% cereal grains (corn, barley, wheat), 20-25% soybean meal, and the balance in fiber sources, minerals, and additives-the appropriate ring die compression ratio falls in the 8:1 to 10:1 range. Fiber-rich swine formulations with significant barley or wheat-bran content require higher compression to generate sufficient frictional heat for starch gelatinization and binding. Hongyang’s engineering team, working from the customer’s actual formulation data, recommended a 9:1 compression ratio with 3.5 mm hole diameter, an effective hole length of 31.5 mm, and a die working width of 140 mm. This specification aimed to balance pellet hardness with throughput, avoiding the over-compression that can cause die plugging, excessive motor load, and heat damage to heat-sensitive feed additives such as enzymes and synthetic amino acids.
Die material and hardening. The selected HYPM ring die used a vacuum-hardened alloy with a surface hardness of 60 HRC and a case depth of 1.5 mm. This material choice was driven by the abrasive nature of the Spanish customer’s raw-material sourcing, which included a portion of locally sourced barley known for its high silica content from soil contamination. Standard carbon-steel dies in similar service conditions had shown accelerated bore wear within 3,000-4,000 operating hours; the HYPM alloy is rated for 5,000-6,000 hours under comparable abrasion loads.
Pellet mill drive and conditioning. The SZLH420 is equipped with a 110 kW main motor driving the ring die via a heavy-duty gearbox with helical gear transmission, rated for continuous operation at 250-350 rpm die speed. Upstream, a double-layer conditioner with a retention time of 45-90 seconds (adjustable via paddle angle) provides steam conditioning at 80-85 degrees C, achieving a post-conditioning moisture content of 15-17% and starch gelatinization rates of 30-35%-both within the optimal window for swine feed pelleting.
4. Installation, Commissioning, and Early Results
The entire installation-from disassembly of the old line to first production on the SZLH420-was completed within 14 days, a timeline enabled by the modular design of Hongyang’s pellet mill frame, which sits on a pre-leveled steel platform requiring no poured-concrete foundation modification.
Commissioning data from the first 30 days of operation showed:
Throughput (grower feed, 3.5 mm): Target >= 8 TPH, Actual (30-Day Average): 9.3 TPH
PDI (tumble-box method): Target >= 92%, Actual: 93.2%
Specific energy consumption: Target <= 16 kWh/t, Actual: 14.8 kWh/t
Fines return rate: Target <= 5%, Actual: 3.1%
Post-conditioning moisture: Target 15-17%, Actual: 16.2%
Starch gelatinization: Target 30-35%, Actual: 33.6%
The PDI result was particularly significant. At 93.2%, the mill was producing pellets that held together through the site’s bucket elevator, rotary screener, and 25-meter pneumatic conveying line to the finished-product silos-and, more importantly, through the 80-120 km truck journey to the pig farms served by the mill. Mill staff reported that fines accumulation at the bottom of bulk delivery trucks dropped by approximately 40% compared to the old line.
5. On-Farm Impact: Why Pellet Quality Matters for Pig Performance
The ultimate test of pelleting equipment is not in the feed mill but in the pig barn. For swine producers, pellet quality directly affects three economic drivers:
Feed intake and growth rate. Studies consistently show that pigs fed high-durability pellets with minimal fines achieve higher average daily feed intake (ADFI) and average daily gain (ADG) compared to those fed mash or crumbled pellets with high fines content. The mechanism is straightforward: fines increase feed wastage, reduce palatability, and cause pigs to spend more time sorting feed rather than consuming it. For the Aragon mill’s customers-primarily grow-to-finish operations with 2,000-5,000 head per site-feed represents 60-70% of total production cost, making even small FCR improvements economically meaningful.
Nutrient uniformity. A well-manufactured pellet ensures that each bite contains the full nutritional profile formulated by the nutritionist. When pellets disintegrate into fines during handling, fines tend to concentrate at the bottom of feeders while intact pellets remain on top, effectively creating two different diets within the same feeder. This segregation undermines the precision nutrition that modern swine genetics demand.
Gut health and feed hygiene. The combination of moisture, temperature, and pressure during pelleting achieves a partial reduction in microbial load, including common feed-borne pathogens. While pelleting is not a sterilization step, the thermal process provides an additional hygiene barrier that complements biosecurity measures at the farm level.
Within six months of the mill’s pelleting line upgrade, two of its largest contract farms reported FCR improvements of 0.08-0.12 points for the grower phase (30-70 kg bodyweight), meaning an estimated saving of 8-12 kg of feed per pig through that growth stage. The mill’s production manager attributes this not solely to the equipment change but to the combination of improved pellet durability and the mill’s decision to tighten its in-process quality checks on a Hongyang-supplied line that provided more consistent output.
6. After-Sales Support as a Competitive Differentiator
One aspect of the Hongyang engagement that the Spanish customer cited as decisive was the availability of technical support beyond the initial installation. For ring die pellet mills, the ring die itself is a consumable item that must be replaced every 5,000-6,000 hours (depending on raw-material abrasiveness and operator maintenance practices). Hongyang maintains a stock of replacement HYPM ring dies in standard compression ratios and hole diameters for the SZLH420, and offers custom die engineering for mills with non-standard formulations.
During the first die changeover at approximately 5,200 operating hours, the customer’s maintenance team encountered a minor alignment issue caused by uneven bolt torque on the die clamp assembly. Hongyang’s technical staff provided remote video guidance within 24 hours, walking the team through a torque-sequence procedure that resolved the issue without production downtime exceeding a single shift. In an industry where a 24-hour stoppage at a 60,000-ton-per-year mill can mean 150-200 tons of lost output, the speed and quality of remote support have tangible economic value.
The customer has since ordered a second HYPM ring die with a slightly modified compression ratio (9.5:1) for a new batch of finisher feed with higher barley inclusion-a formulation adjustment driven by seasonal raw-material availability in the Ebro Valley. Hongyang’s willingness to produce single-unit custom dies rather than requiring minimum-order quantities of five or more was, in the customer’s words, “the difference between a supplier and a partner.”
7. Conclusion
The Spanish swine feed market is one of the most sophisticated in the world-high volume, price-sensitive, and technically demanding. For equipment manufacturers seeking to enter or expand in this market, the barriers are not merely commercial but technical: pellet durability, throughput consistency, energy efficiency, and after-sales responsiveness are the real currencies of competition.
Hongyang Feed Machinery’s SZLH420 ring die pellet mill and HYPM ring die system demonstrated that a mid-range Chinese-manufactured pelleting line can meet or exceed the performance expectations of a quality-driven European feed mill. The combination of correct compression ratio engineering, high-grade die material, and responsive technical support produced measurable results: PDI above 93%, throughput of 9-10 TPH, energy consumption of 14.8 kWh/t, and downstream FCR improvements that matter to the pig farmer’s bottom line.
For feed millers evaluating pelleting equipment, the Aragon case underscores three principles worth carrying into any procurement decision: first, invest the time to match ring die compression ratio to your actual formulations rather than relying on generic specifications; second, treat after-sales support capability as a selection criterion equal to price and technical specifications; and third, measure equipment performance not by the datasheet but by the feed conversion results at the farm gate-because that is where every ultimately proves its worth.
Post time: Jun-10-2026
