{"id":"wpc-tech100-article-017-en","slug":"die-swell-and-dimensional-control-of-wpc","locale":"en","url":"https://woodplasticcomposite.net/guides/die-swell-and-dimensional-control-of-wpc/","title":"Die swell and dimensional control of WPC","answer":"Dimensions at the die exit are not necessarily the final dimensions of a cooled WPC profile. Die design, material response and downstream handling must be considered together.","author":"NFC & WPC Knowledge Reference","faqIds":["wpc-tech100-faq-017-en"],"tagIds":[],"noindex":false,"related":["wpc-tech100-article-018-en"],"version":1,"modified":"2026-10-15","reviewer":"","sections":[{"id":"technical-context","text":"A change in formulation or process conditions can alter the relationship between die geometry and the final cross-section. Measuring only the finished width leaves uncertainty about where the dimensional change occurred.","heading":"Technical context","references":[],"url":"https://woodplasticcomposite.net/guides/die-swell-and-dimensional-control-of-wpc/#technical-context"},{"id":"verification-plan","text":"Create an approved measurement plan at relevant process stages, using safe non-contact methods where appropriate. Record line speed, material lot and thermal conditions. Compare multiple profile locations rather than assuming uniform behaviour across a complicated section.","heading":"What to measure and document","references":[],"url":"https://woodplasticcomposite.net/guides/die-swell-and-dimensional-control-of-wpc/#verification-plan"},{"id":"practical-decision","text":"Do not correct every dimensional deviation by changing haul-off speed. Diagnose whether the source is flow, cooling, calibration or measurement first. A stable final geometry should be verified with a defined tolerance and sampling frequency.","heading":"Implications for development and specification","references":[],"url":"https://woodplasticcomposite.net/guides/die-swell-and-dimensional-control-of-wpc/#practical-decision"},{"id":"reading-scope","text":"A research comparison of laboratory and on-line WPC flow measurements. Use the linked work as related reading. The practical checks above are editorial recommendations, not reported test results or a substitute for product qualification.","heading":"Related reading and evidence limits","references":[1],"url":"https://woodplasticcomposite.net/guides/die-swell-and-dimensional-control-of-wpc/#reading-scope"}],"seoTitle":"Die swell and dimensional control of WPC | WPC Reference","topicIds":[],"published":"2026-10-15","tableText":"Review step | Evidence to retain\nMaterial and geometry | Exact specimen or product identity\nVerification | Method, conditions and individual observations\nDecision | Approved scope and documented limitations","takeaways":"A change in formulation or process conditions can alter the relationship between die geometry and the final cross-section.\nCreate an approved measurement plan at relevant process stages, using safe non-contact methods where appropriate.\nDo not correct every dimensional deviation by changing haul-off speed.","aiAssisted":true,"categoryId":"wpc-tech100-category-1","reviewedAt":"","change_note":"New focused technical draft; not a product certification or production recipe.","description":"Dimensions at the die exit are not necessarily the final dimensions of a cooled WPC profile.","heroImageId":"","referenceIds":["wpc-tech100-ref-rheology"],"review_status":"AI-assisted English editorial draft. Human technical review has not been recorded.","table_caption":"Evidence checklist for die swell and dimensional control of wpc","seoDescription":"Dimensions at the die exit are not necessarily the final dimensions of a cooled WPC profile.","translationGroup":"wpc-tech100-017-2026","references":[{"url":"https://doi.org/10.3390/polym17202782","type":"web","title":"Rheology for WPC extrusion: laboratory vs on-line rheometry","noindex":false,"accessed":"2026-10-14","seoTitle":"Rheology for WPC extrusion: laboratory vs on-line rheometry","publisher":"Polymers","description":"Related reading; scope and limitations are identified in each article.","seoDescription":"Related reading; scope and limitations are identified in each article."}],"faqs":[{"question":"What evidence is needed for die swell and dimensional control of WPC?","answer":"Create an approved measurement plan at relevant process stages, using safe non-contact methods where appropriate. Record line speed, material lot and thermal conditions. Compare multiple profile locations rather than assuming uniform behaviour across a complicated section."}]}