# Casting Defect Troubleshooting Checklist: Porosity, Shrinkage, Sand and Metal Faults > Source: https://netray.co/tools/casting-defect-troubleshooting-checklist > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer A practical checklist of what to check when castings show gas porosity, shrinkage, inclusions, sand defects, cracks or dimensional problems. ## Category quality ## Industry Foundry ## Audience - Foundry quality engineer - Process engineer - Melt deck supervisor - Molding supervisor ## Tool **Kind:** checklist **Groups:** #### Gas porosity and pinholes **Items:** **Text:** Check mold and core moisture and binder gas generation against limits **Critical:** true Confirm core vents are open and core prints are sealed to the mold Check mold permeability and venting at the last place to fill **Text:** Check metal hydrogen level, degassing time and dross removal (aluminium) **Critical:** true Check pouring temperature is not too high and metal was not held too long Inspect chills and chaplets for rust or moisture Review charge material for oil, water, rust and coatings #### Shrinkage and feeding **Items:** Locate the defect at a hot spot, thick junction or last-to-freeze region **Text:** Check riser size, neck size and feeding distance against the casting modulus **Critical:** true Check riser height and whether riser sleeves or topping compound were used Review pouring temperature, since high temperature increases liquid contraction Check chill placement and whether it was in position at pour Check mold wall movement from soft ramming or low mold hardness **Text:** For ductile iron, check carbon equivalent and inoculation practice **Critical:** true #### Inclusions, slag and dross **Items:** **Text:** Check ladle skimming, slag removal and clean pour lip **Critical:** true Confirm gating includes a choke, a runner extension or filter where designed Check filter size, placement and preheat Review magnesium treatment fade and slag carryover for nodular iron Check for oxide films from turbulent filling or high ingate velocity Check refractory lining and ladle condition for erosion #### Sand and mold defects **Items:** **Text:** Check green strength, compactibility, moisture and permeability at the muller **Critical:** true Check for sand wash or erosion at ingates and sharp corners Look for scabs and buckles; check clay, sand expansion and mold coating Check for burn-on and penetration; verify coating, grain fineness and pouring temperature Check mold closing, cope drop, crush or mismatch at the parting line Confirm core setting, core print fit and core shift Check mold hardness and ramming consistency #### Cracks, tears and distortion **Items:** **Text:** Distinguish hot tears (oxidised, jagged) from cold cracks (clean, straight) **Critical:** true Check for abrupt section changes and missing radii or fillets Check mold and core collapsibility, since hard cores restrain contraction Check shakeout time and cooling rate before knock-out Review heat treatment or straightening steps after casting Check for cold shuts and misruns from low pouring temperature or slow pour #### Dimensions and records **Items:** Check the pattern against the drawing and the shrink allowance used Check pattern wear, loose parts and rapping allowance **Text:** Record the heat number, pour time, pour temperature and mold number of the faulty castings **Critical:** true Retain samples and photographs for the root cause file **Text:** Open a nonconformance and containment for suspect lots **Critical:** true Update scrap codes so defects are counted consistently **Scoring Note:** Tick each check you have completed. Start with the group matching the defect appearance, then review records. The list does not replace metallurgical examination, radiography or sectioning when the cause is not clear. ## Content **Intro:** When castings start to fail inspection, speed matters. This checklist lists what experienced foundry people check, grouped by the type of defect, so you can work through likely causes in order instead of guessing. Print it or save it as a PDF for the shift review. **Sections:** #### How to use the checklist **Body:** Start by naming the defect from its appearance and location. A rounded smooth cavity is usually gas, a rough dendritic cavity at a hot spot is usually shrinkage, and a spongy area at the surface may be sand or core gas. Go to the matching group and tick off each check. Items marked critical are the ones most often found to be the cause. Record findings with the heat, mold and time so you can find a pattern across shifts. #### Gas or shrinkage **Body:** Confusing gas porosity with shrinkage leads to the wrong fix. Gas defects are usually spherical, smooth and often near the surface or under cores, and respond to venting, drier sand and degassing. Shrinkage is angular or dendritic and sits at heavy sections away from risers, and responds to better feeding, chills and pouring temperature control. Increasing riser size to fix gas defects wastes metal, and degassing more will not cure shrinkage. **Bullets:** - Smooth round cavity: suspect gas - Rough interior, dendrites: suspect shrinkage - Surface slag or dross stringers: suspect inclusions - Cavity under a core: check core gas and venting #### Closing the loop **Body:** A defect fix is only proven when scrap falls over many molds, not after one good shot. Change one variable at a time and note it in the process log. Monitor the scrap code for at least a week. Use sectioning, X-ray or dye penetrant testing on sample castings to confirm the defect type before spending on tooling changes. For safety-critical or customer-reported failures, run a formal 8D or corrective action report. #### Common mistakes and ERP notes **Body:** Most foundries lose time because scrap is coded loosely, such as a single 'defective' reason. Use specific reason codes so Pareto charts mean something. In the ERP or MES, tie scrap and rework quantities to the heat, mold line and pattern so trends can be seen. Without heat and mold traceability the checklist yields opinions rather than evidence. **Cta:** If scrap reasons and heat numbers are not captured consistently in your ERP, we can help set up the codes and reports that make defect trends visible. **Faq:** #### How do I tell gas porosity from shrinkage porosity? **Answer:** Gas porosity tends to be smooth, round and sometimes shiny, while shrinkage is rough, angular or dendritic and appears at the last-to-freeze section. Sectioning the casting and examining the cavity wall usually settles it. #### What causes hot tears in castings? **Answer:** Hot tears form while the casting is still weak and is restrained from contracting, often at sharp section changes or where cores and mold resist movement. Better radii, more collapsible cores and controlled pour temperature help. #### Should I change the riser or the pouring temperature first? **Answer:** Confirm the defect type first. Shrinkage points to feeding and temperature; gas points to venting, moisture and metal quality. Change one variable at a time and track scrap over many molds. #### Does this checklist cover die casting? **Answer:** It is written mainly for sand casting. Many ideas, such as gas, shrinkage and inclusions, carry across, but die casting adds shot profile, die temperature and lubricant factors that need their own list. ## Search terms casting defect troubleshooting checklist, casting defects causes and remedies, gas porosity vs shrinkage porosity, sand casting defects checklist, foundry scrap root cause, casting defect analysis, hot tear casting cause, foundry quality checklist --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json