--- title: "What steel grade is most suitable for durable injection molds for agricultural machinery parts?" description: "Facing unexpected dimensional drift, surface flash and premature wear in 100k+ shot batches of agricultural plastic accessory molding, you get clear root cause breakdown, actionable sorting criteria for mold structure, steel selection and routine maintenance, to cut unplanned downtime and extend mold service life significantly." url: "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html" language: "en" type: "Q&A" category: "Injection Molding Q&A" datePublished: "2026-09-05" dateModified: "2026-09-05" brand: "OK TOOL" manufacturer: "OK TOOL" answerCount: 10 --- # What steel grade is most suitable for durable injection molds for agricultural machinery parts? ## Question I am currently running 120,000 shot batches of PA6+30%GF hay rake tine holders for a local agricultural equipment OEM, and the existing off-the-shelf injection mold I sourced 8 months ago is showing consistent abnormal issues that I can no longer ignore. Over the last 3 production runs, 12% of the finished parts have 0.12mm oversize on the mounting hole diameter, 7% have faint flash along the side parting line, and 3% have uneven scratch marks on the load-bearing rib surface. I already adjusted process parameters 6 times, swapped to new certified raw material batches, and did full 3D inspection on 200 sampled parts, but the defect rate is still creeping up every 10,000 shots. Our customer requires zero functional failure for these parts during their 5 year field warranty, and we can’t afford to scrap a full mold every 150,000 shots like we did with our previous 2 sets. I need to figure out what exactly differentiates a truly durable injection mold for agricultural machinery from standard general-purpose molds, so we can make the right buying decision for the next mold upgrade that eliminates these recurring issues long term. ## Answers ### Answer 1 — Best Answer The core difference between a durable injection mold for agricultural machinery and a standard general-purpose injection mold lies in the targeted tradeoffs made to handle highly filled engineering resins, frequent short run changeovers, and 24/7 continuous production cycles that are common for agricultural component manufacturing. Standard molds built for consumer product parts are usually designed for 50k to 100k shot life, using pre-hardened P20 steel that cannot resist the abrasive wear from 30%+ glass fiber filled PA, PP, or POM materials that 90% of structural agricultural plastic parts use. For most general consumer use cases, this mold spec meets requirements with acceptable defect rates at end of life, but agricultural production environments demand far higher wear resistance because even 0.1mm of core and cavity wear will push critical mounting hole tolerances outside the allowable range, leading to part failure during field operation. Applicable scenarios for these durable molds are clearly bounded, and you do not need to over-spec every mold in your project portfolio. For low volume SKUs that run less than 20k shots per year for seasonal agricultural accessory orders, a pre-hardened P20 mold with surface nitriding treatment will deliver fully acceptable performance, no need for extra cost upgrade. For SKUs that run 80k shots or more annually, especially parts with load bearing ribs, sharp corners, or high tolerance mounting features, you need to specify at least H13 or 1.2344 hot work steel for core and cavity inserts. Parts that come into direct contact with soil, fertilizer or harsh outdoor UV exposure, such as sprayer nozzles or hay rake components, will require even higher performance steel, paired with properly sized gate locations that reduce shear wear on the mold surface. **Start your selection validation with 3 non-negotiable checks before you confirm any mold order**, to avoid paying premium pricing for a mold that does not deliver the expected life extension. First, confirm the core and cavity steel hardness test report before the first rough machining step, not after the mold is fully finished, to make sure the actual HRC value meets your specified requirement. **Second, add a mandatory 2000 shot continuous dry run and 100% dimensional inspection of 50 sampled parts at the 1000 shot mark during mold trial**, to catch any unbalanced ejection or parting line mismatch issues before the mold is shipped to your production line. **Third, lock in a 12 month mold warranty that covers both dimensional stability and normal abrasive wear, not just manufacturing defects**, so you do not absorb the full cost of rework if the mold wears out earlier than the agreed shot life. The expected service life of a properly built durable agricultural machinery injection mold can hit 500k to 1 million shots, which cuts your per part tooling amortization cost by 60% compared to standard general purpose molds. **status:** accepted **Author:** Eric Zhao **Date:** 2026-09-05 ### Answer 2 All core and cavity inserts need to be machined with a consistent 0.01mm tolerance on all mating surfaces, instead of the 0.03mm standard tolerance used for consumer part molds. A climb milling strategy is applied for all high wear edges, which reduces residual stress on the mold surface after heat treatment, so there is almost no post machining deformation that can cause parting line offset later. Fixture design during rough machining holds the entire mold plate with full surface support instead of edge clamping, which eliminates uneven force that can cause micro deformation after 100k+ shots. The surface finish of all flow paths is controlled to Ra 0.8 or better, which reduces glass fiber deposition on the mold wall that causes scratch marks on finished parts, no extra manual polishing work needed after heat treatment. **status:** suggested **Author:** Linda Xu **Date:** 2026-09-05 ### Answer 3 All mold plate mating surfaces use a 0.005mm interference fit for all guide pins and guide bushes, instead of the standard 0.01mm clearance fit used for general purpose molds. This eliminates the lateral movement of the moving half of the mold that causes uneven flash along the parting line after tens of thousands of shots. All ejector pins sit 0.002mm below the core surface in the initial assembly, and 0.1mm thick wear plates are added under all ejector plates to prevent sagging that causes inconsistent ejection marks on the load bearing ribs. Full tolerance stack up simulation is done before final assembly, to make sure even after 300k shots of normal wear, the total accumulated dimensional deviation will not push the mounting hole diameter outside the allowable 0.05mm tolerance range, so no unplanned rework is needed mid production run. **status:** suggested **Author:** Michael Wu **Date:** 2026-09-05 ### Answer 4 The entire mold development timeline is structured with 5 gated checkpoints that you can sign off at each stage, no hidden progress that leads to unexpected delays. After 2D design finalization, you get a full DFM report for review before any steel is cut, so all feature adjustments that help extend mold life are confirmed before machining starts. 3 separate sample batches are arranged: 50 shots at the first trial, 200 shots after minor adjustment, and 1000 shots for continuous stability testing, before final sample sign off. All change requests that come up during production trial are logged in a shared tracking sheet, so there is no miscommunication that leads to conflicting requirements between different teams. A full mold operation manual with all recommended maintenance intervals is handed over together with the mold when it is shipped to your facility. **status:** suggested **Author:** Rachel Huang **Date:** 2026-09-05 ### Answer 5 A wide process window is built into every durable agricultural machinery mold, so you can run the part stably even if there is small fluctuation in raw material melt index, or minor variation in ambient temperature on your production floor in different seasons. The gating system is designed to keep injection pressure below 1200 bar for 30% GF filled PA materials, which reduces unnecessary shear force that causes excessive abrasion on the mold core surface. The pre-optimized cooling line layout keeps the mold temperature difference across the entire core surface below 3 degrees C, which eliminates uneven thermal expansion that causes dimensional drift of the mounting holes after long continuous production runs. All recommended process parameters are documented during the mold trial, so your production team can start running the mold at full speed immediately after arrival, no long parameter debugging period needed. **status:** suggested **Author:** David Zhang **Date:** 2026-09-05 ### Answer 6 All sharp corners on the load bearing ribs of the part are designed with a minimum 0.3mm radius at the mold side, instead of the 0.1mm radius that some designers use to match exact part drawing requirements. This eliminates stress concentration points on the mold surface that can crack after repeated high pressure injection cycles. All gate locations are placed at the thickest section of the part, so the highly filled resin does not flow directly across narrow core pins that form the mounting holes, which drastically reduces abrasive wear on those high tolerance features. A separate vent insert is installed along the parting line near the end of fill, which eliminates trapped air that causes burning marks on the part surface, and removes the need for operators to manually polish the parting line every few thousand shots. **status:** suggested **Author:** Kevin Liu **Date:** 2026-09-05 ### Answer 7 The mold is designed to run on standard 180 ton to 300 ton injection molding machines with no special modification required, so you can allocate it to any available production press on your shop floor without extra fixture upgrade work. The overall cycle time is optimized to be no more than 10% longer than a standard low durability mold for the same part, so there is no major drop in your daily production output. All standard components such as ejector pins, cooling fittings and guide bushes are sourced from global well-known brands with local stock support in your region, so you can get replacement parts delivered within 24 hours if any unexpected wear occurs, no long lead time custom part ordering that stops your production line for days. The mold mounting plates are standardized to match your existing press mounting hole patterns, so the first mold changeover can be completed in less than 30 minutes. **status:** suggested **Author:** Emily Chen **Date:** 2026-09-05 ### Answer 8 For the specific PA6+30%GF hay rake tine holder parts you are running, there is no need to use extra expensive powder metallurgy steel that doubles the total mold cost. Nitrided H13 hot work steel for core and cavity inserts delivers the best cost performance, with expected abrasive wear resistance 3 times higher than standard P20 steel, at only 40% higher total tooling cost. For parts that use 40% or higher glass fiber filled resin, you can upgrade to 1.2379 tool steel if the expected annual shot volume is over 200k, which will extend total mold life to over 1 million shots. Surface coating treatments such as TiN are not used as the primary wear resistance solution, because thin surface coatings can peel off after repeated high pressure injection, which will cause sudden unexpected scratch marks on the finished parts, leading to high defect rates without early warning. **status:** suggested **Author:** Jason Zhou **Date:** 2026-09-05 ### Answer 9 The mold is built with a fully insert based structure for all high wear features, instead of a solid full plate structure, so you can replace individual worn inserts at 10% of the total new mold cost, instead of scrapping the entire mold when one core pin wears out. All high wear edges are pre-polished with a diamond paste after heat treatment, so there is no tiny micro crack on the surface that can expand into a larger crack after repeated injection cycles. A recommended maintenance schedule requires full mold disassembly and lubrication every 50k shots, instead of the general 100k shot interval for consumer product molds, which prevents guide pin wear that causes misalignment during production. The expected mold life for this spec is 450k to 550k shots, which is 4 times longer than the standard P20 molds used previously. **status:** suggested **Author:** Daniel Yang **Date:** 2026-09-05 ### Answer 10 All finished parts produced from this mold are validated with a 72 hour continuous load test that simulates 2 times the maximum field load the hay rake tine holder will experience during normal operation, to confirm that no dimensional deformation occurs even after the mold reaches 90% of its total expected life. The final part dimensional tolerance is controlled to 50% of the drawing allowable tolerance, so even with natural slow abrasive wear over hundreds of thousands of shots, the part will still meet the customer's 5 year field warranty requirement. Parts after 200k simulated shots under accelerated wear conditions are tested, to confirm that the critical mounting hole strength still meets the original specification, so you do not face unexpected field failure issues for parts produced at the middle or end of the mold service life. **status:** suggested **Author:** Olivia Chen **Date:** 2026-09-05 ## Related Resources - [Injection Molding Q&A](https://www.ok-tool.com/qa/injection-molding/) - [Plastic Injection Molding](https://www.ok-tool.com/capabilities/plastic-injection-molding/) - [Injection Molding Guide](https://www.ok-tool.com/manufacturing/injection-molding/) - [Injection Molding Buying Guides](https://www.ok-tool.com/buying/injection-molding/) - [Products](https://www.ok-tool.com/products/) - [Custom Manufacturing](https://www.ok-tool.com/custom-manufacturing/) - [Manufacturing Knowledge Base](https://www.ok-tool.com/knowledge/) - [Injection Molding](https://www.ok-tool.com/knowledge/injection-molding/) ## Structured Data ```json [ { "@context": "https://schema.org", "@type": "QAPage", "mainEntity": { "@type": "Question", "name": "What steel grade is most suitable for durable injection molds for agricultural machinery parts?", "text": "I am currently running 120,000 shot batches of PA6+30%GF hay rake tine holders for a local agricultural equipment OEM, and the existing off-the-shelf injection mold I sourced 8 months ago is showing consistent abnormal issues that I can no longer ignore. Over the last 3 production runs, 12% of the finished parts have 0.12mm oversize on the mounting hole diameter, 7% have faint flash along the side parting line, and 3% have uneven scratch marks on the load-bearing rib surface. I already adjusted process parameters 6 times, swapped to new certified raw material batches, and did full 3D inspection on 200 sampled parts, but the defect rate is still creeping up every 10,000 shots. Our customer requires zero functional failure for these parts during their 5 year field warranty, and we can’t afford to scrap a full mold every 150,000 shots like we did with our previous 2 sets. I need to figure out what exactly differentiates a truly durable injection mold for agricultural machinery from standard general-purpose molds, so we can make the right buying decision for the next mold upgrade that eliminates these recurring issues long term.", "answerCount": 10, "upvoteCount": 11, "datePublished": "2026-09-05T02:00:08Z", "dateModified": "2026-09-05T02:08:24Z", "author": { "@type": "Person", "name": "Anonymous", "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html" } ,"acceptedAnswer": { "@type": "Answer", "text": "The core difference between a durable injection mold for agricultural machinery and a standard general-purpose injection mold lies in the targeted tradeoffs made to handle highly filled engineering resins, frequent short run changeovers, and 24/7 continuous production cycles that are common for agricultural component manufacturing. Standard molds built for consumer product parts are usually designed for 50k to 100k shot life, using pre-hardened P20 steel that cannot resist the abrasive wear from 30%+ glass fiber filled PA, PP, or POM materials that 90% of structural agricultural plastic parts use. For most general consumer use cases, this mold spec meets requirements with acceptable defect rates at end of life, but agricultural production environments demand far higher wear resistance because even 0.1mm of core and cavity wear will push critical mounting hole tolerances outside the allowable range, leading to part failure during field operation. Applicable scenarios for these durable molds are clearly bounded, and you do not need to over-spec every mold in your project portfolio. For low volume SKUs that run less than 20k shots per year for seasonal agricultural accessory orders, a pre-hardened P20 mold with surface nitriding treatment will deliver fully acceptable performance, no need for extra cost upgrade. For SKUs that run 80k shots or more annually, especially parts with load bearing ribs, sharp corners, or high tolerance mounting features, you need to specify at least H13 or 1.2344 hot work steel for core and cavity inserts. Parts that come into direct contact with soil, fertilizer or harsh outdoor UV exposure, such as sprayer nozzles or hay rake components, will require even higher performance steel, paired with properly sized gate locations that reduce shear wear on the mold surface. Start your selection validation with 3 non-negotiable checks before you confirm any mold order , to avoid paying premium pricing for a mold that does not deliver the expected life extension. First, confirm the core and cavity steel hardness test report before the first rough machining step, not after the mold is fully finished, to make sure the actual HRC value meets your specified requirement. Second, add a mandatory 2000 shot continuous dry run and 100% dimensional inspection of 50 sampled parts at the 1000 shot mark during mold trial , to catch any unbalanced ejection or parting line mismatch issues before the mold is shipped to your production line. Third, lock in a 12 month mold warranty that covers both dimensional stability and normal abrasive wear, not just manufacturing defects , so you do not absorb the full cost of rework if the mold wears out earlier than the agreed shot life. The expected service life of a properly built durable agricultural machinery injection mold can hit 500k to 1 million shots, which cuts your per part tooling amortization cost by 60% compared to standard general purpose molds.", "upvoteCount": 11, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#acceptedAnswer", "datePublished": "2026-09-05T02:57:43Z", "author": {"@type": "Person","name": "Eric Zhao","url": "https://www.ok-tool.com/team/eric.html"} } ,"suggestedAnswer": [ { "@type": "Answer", "text": "All core and cavity inserts need to be machined with a consistent 0.01mm tolerance on all mating surfaces, instead of the 0.03mm standard tolerance used for consumer part molds. A climb milling strategy is applied for all high wear edges, which reduces residual stress on the mold surface after heat treatment, so there is almost no post machining deformation that can cause parting line offset later. Fixture design during rough machining holds the entire mold plate with full surface support instead of edge clamping, which eliminates uneven force that can cause micro deformation after 100k+ shots. The surface finish of all flow paths is controlled to Ra 0.8 or better, which reduces glass fiber deposition on the mold wall that causes scratch marks on finished parts, no extra manual polishing work needed after heat treatment.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-2", "datePublished": "2026-09-05T02:54:31Z", "author": {"@type": "Person","name": "Linda Xu","url": "https://www.ok-tool.com/team/linda.html"} } , { "@type": "Answer", "text": "All mold plate mating surfaces use a 0.005mm interference fit for all guide pins and guide bushes, instead of the standard 0.01mm clearance fit used for general purpose molds. This eliminates the lateral movement of the moving half of the mold that causes uneven flash along the parting line after tens of thousands of shots. All ejector pins sit 0.002mm below the core surface in the initial assembly, and 0.1mm thick wear plates are added under all ejector plates to prevent sagging that causes inconsistent ejection marks on the load bearing ribs. Full tolerance stack up simulation is done before final assembly, to make sure even after 300k shots of normal wear, the total accumulated dimensional deviation will not push the mounting hole diameter outside the allowable 0.05mm tolerance range, so no unplanned rework is needed mid production run.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-3", "datePublished": "2026-09-05T02:51:14Z", "author": {"@type": "Person","name": "Michael Wu","url": "https://www.ok-tool.com/team/michael.html"} } , { "@type": "Answer", "text": "The entire mold development timeline is structured with 5 gated checkpoints that you can sign off at each stage, no hidden progress that leads to unexpected delays. After 2D design finalization, you get a full DFM report for review before any steel is cut, so all feature adjustments that help extend mold life are confirmed before machining starts. 3 separate sample batches are arranged: 50 shots at the first trial, 200 shots after minor adjustment, and 1000 shots for continuous stability testing, before final sample sign off. All change requests that come up during production trial are logged in a shared tracking sheet, so there is no miscommunication that leads to conflicting requirements between different teams. A full mold operation manual with all recommended maintenance intervals is handed over together with the mold when it is shipped to your facility.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-4", "datePublished": "2026-09-05T02:41:28Z", "author": {"@type": "Person","name": "Rachel Huang","url": "https://www.ok-tool.com/team/rachel.html"} } , { "@type": "Answer", "text": "A wide process window is built into every durable agricultural machinery mold, so you can run the part stably even if there is small fluctuation in raw material melt index, or minor variation in ambient temperature on your production floor in different seasons. The gating system is designed to keep injection pressure below 1200 bar for 30% GF filled PA materials, which reduces unnecessary shear force that causes excessive abrasion on the mold core surface. The pre-optimized cooling line layout keeps the mold temperature difference across the entire core surface below 3 degrees C, which eliminates uneven thermal expansion that causes dimensional drift of the mounting holes after long continuous production runs. All recommended process parameters are documented during the mold trial, so your production team can start running the mold at full speed immediately after arrival, no long parameter debugging period needed.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-5", "datePublished": "2026-09-05T02:38:36Z", "author": {"@type": "Person","name": "David Zhang","url": "https://www.ok-tool.com/team/david.html"} } , { "@type": "Answer", "text": "All sharp corners on the load bearing ribs of the part are designed with a minimum 0.3mm radius at the mold side, instead of the 0.1mm radius that some designers use to match exact part drawing requirements. This eliminates stress concentration points on the mold surface that can crack after repeated high pressure injection cycles. All gate locations are placed at the thickest section of the part, so the highly filled resin does not flow directly across narrow core pins that form the mounting holes, which drastically reduces abrasive wear on those high tolerance features. A separate vent insert is installed along the parting line near the end of fill, which eliminates trapped air that causes burning marks on the part surface, and removes the need for operators to manually polish the parting line every few thousand shots.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-6", "datePublished": "2026-09-05T02:37:18Z", "author": {"@type": "Person","name": "Kevin Liu","url": "https://www.ok-tool.com/team/kevin.html"} } , { "@type": "Answer", "text": "The mold is designed to run on standard 180 ton to 300 ton injection molding machines with no special modification required, so you can allocate it to any available production press on your shop floor without extra fixture upgrade work. The overall cycle time is optimized to be no more than 10% longer than a standard low durability mold for the same part, so there is no major drop in your daily production output. All standard components such as ejector pins, cooling fittings and guide bushes are sourced from global well-known brands with local stock support in your region, so you can get replacement parts delivered within 24 hours if any unexpected wear occurs, no long lead time custom part ordering that stops your production line for days. The mold mounting plates are standardized to match your existing press mounting hole patterns, so the first mold changeover can be completed in less than 30 minutes.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-7", "datePublished": "2026-09-05T02:24:04Z", "author": {"@type": "Person","name": "Emily Chen","url": "https://www.ok-tool.com/team/emily.html"} } , { "@type": "Answer", "text": "For the specific PA6+30%GF hay rake tine holder parts you are running, there is no need to use extra expensive powder metallurgy steel that doubles the total mold cost. Nitrided H13 hot work steel for core and cavity inserts delivers the best cost performance, with expected abrasive wear resistance 3 times higher than standard P20 steel, at only 40% higher total tooling cost. For parts that use 40% or higher glass fiber filled resin, you can upgrade to 1.2379 tool steel if the expected annual shot volume is over 200k, which will extend total mold life to over 1 million shots. Surface coating treatments such as TiN are not used as the primary wear resistance solution, because thin surface coatings can peel off after repeated high pressure injection, which will cause sudden unexpected scratch marks on the finished parts, leading to high defect rates without early warning.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-8", "datePublished": "2026-09-05T02:17:28Z", "author": {"@type": "Person","name": "Jason Zhou","url": "https://www.ok-tool.com/team/jason.html"} } , { "@type": "Answer", "text": "The mold is built with a fully insert based structure for all high wear features, instead of a solid full plate structure, so you can replace individual worn inserts at 10% of the total new mold cost, instead of scrapping the entire mold when one core pin wears out. All high wear edges are pre-polished with a diamond paste after heat treatment, so there is no tiny micro crack on the surface that can expand into a larger crack after repeated injection cycles. A recommended maintenance schedule requires full mold disassembly and lubrication every 50k shots, instead of the general 100k shot interval for consumer product molds, which prevents guide pin wear that causes misalignment during production. The expected mold life for this spec is 450k to 550k shots, which is 4 times longer than the standard P20 molds used previously.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-9", "datePublished": "2026-09-05T02:15:24Z", "author": {"@type": "Person","name": "Daniel Yang","url": "https://www.ok-tool.com/team/daniel.html"} } , { "@type": "Answer", "text": "All finished parts produced from this mold are validated with a 72 hour continuous load test that simulates 2 times the maximum field load the hay rake tine holder will experience during normal operation, to confirm that no dimensional deformation occurs even after the mold reaches 90% of its total expected life. The final part dimensional tolerance is controlled to 50% of the drawing allowable tolerance, so even with natural slow abrasive wear over hundreds of thousands of shots, the part will still meet the customer's 5 year field warranty requirement. Parts after 200k simulated shots under accelerated wear conditions are tested, to confirm that the critical mounting hole strength still meets the original specification, so you do not face unexpected field failure issues for parts produced at the middle or end of the mold service life.", "upvoteCount": 0, "url": "https://www.ok-tool.com/qa/best-steel-grade-durable-injection-molds-agricultural-machinery-parts.html#suggestedAnswer-10", "datePublished": "2026-09-05T02:08:24Z", "author": {"@type": "Person","name": "Olivia Chen","url": "https://www.ok-tool.com/team/olivia.html"} } ] } }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ {"@type": "ListItem", "position": 1, "name": "Home", "item": "https://www.ok-tool.com/"},{"@type": "ListItem", "position": 2, "name": "Q&A", "item": "https://www.ok-tool.com/qa/"},{"@type": "ListItem", "position": 3, "name": "Injection Molding Q&A >", "item": "https://www.ok-tool.com/qa/injection-molding/>"} ,{"@type": "ListItem", "position": 4, "name": "What steel grade is most suitable for durable injection molds for agricultural machinery parts?"} ] } ] ```