# Injection Mold Gate Types Reference > Source: https://netray.co/tools/injection-mold-gate-types-reference > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer A comparison table of common mold gate types with where each works best, trade-offs and how the gate is removed. ## Category engineering-plm ## Industry Plastics and Injection Molding ## Audience - Mold designer - Process engineer - Product designer ## Tool **Kind:** worksheet **Mode:** reference **Columns:** #### Gate type **Key:** gate **Type:** text #### Description **Key:** desc **Type:** text #### Best for **Key:** best **Type:** text #### Advantages **Key:** pros **Type:** text #### Drawbacks **Key:** cons **Type:** text #### Gate removal **Key:** degate **Type:** text **Rows:** **Gate:** Sprue gate **Desc:** Melt flows directly from the sprue into the cavity **Best:** Single cavity, large or thick parts, round parts **Pros:** Low pressure loss, simple tool, good pack **Cons:** Large gate vestige, needs manual removal, stress at the gate **Degate:** Manual cut or trim **Gate:** Edge gate **Desc:** Rectangular gate at the parting line feeding the edge of the part **Best:** Flat parts, multi-cavity tools, general purpose parts **Pros:** Easy to machine and modify, good packing, flexible location **Cons:** Gate mark on part edge, runner must be removed **Degate:** Manual or automatic trim **Gate:** Fan gate **Desc:** Edge gate that widens like a fan across the cavity edge **Best:** Wide flat parts, thin panels, reducing warpage **Pros:** Even flow front, lower shear, less orientation **Cons:** Larger vestige to trim **Degate:** Trim **Gate:** Film (flash) gate **Desc:** Very wide thin gate along the full part edge **Best:** Thin flat parts, lenses, parts needing low warpage **Pros:** Uniform fill, low orientation and stress **Cons:** Large gate area to remove, hard to trim cleanly **Degate:** Trim or die cut **Gate:** Tab gate **Desc:** Small tab between gate and part to move shear away from the part **Best:** Parts sensitive to gate stress, clear resins, jetting prevention **Pros:** Moves gate stress and jetting off the part, good surface **Cons:** Extra step to remove tab **Degate:** Manual trim **Gate:** Pin-point gate (three-plate) **Desc:** Small round gate fed by a runner between two plates **Best:** Multi-cavity tools, center gating of cup-shaped parts **Pros:** Small vestige, automatic degating, center gating possible **Cons:** Three-plate mold is more complex, runner waste, higher pressure loss **Degate:** Automatic when mold opens **Gate:** Submarine (tunnel) gate **Desc:** Gate angled below the parting line into the part **Best:** Small to medium parts, automatic degating of runner **Pros:** Automatic degating, small mark, no separate trim **Cons:** Not for brittle or very stiff resins, gate wear, needs ejector design **Degate:** Automatic at ejection **Gate:** Cashew (banana) gate **Desc:** Curved submarine gate that enters from the ejector side **Best:** Parts that need gating on an inside surface, hidden gates **Pros:** Gate mark can be hidden, automatic degating **Cons:** Complex to machine, limited resin suitability **Degate:** Automatic at ejection **Gate:** Ring gate **Desc:** Melt flows around a core through a ring before entering the cavity **Best:** Cylindrical or tubular parts **Pros:** Even filling around the part, reduces weld lines and eccentricity **Cons:** Needs trimming of the ring, more material **Degate:** Machined or trimmed off **Gate:** Diaphragm gate **Desc:** Disc-shaped gate across the inside of a hollow part **Best:** Round hollow parts such as bottle caps or gears, concentric parts **Pros:** Uniform concentric fill, no weld lines, good roundness **Cons:** Disc must be removed, cut mark inside **Degate:** Machined or punched off **Gate:** Hot tip gate **Desc:** Hot runner nozzle with heated tip directly gating the part **Best:** High-volume parts, runnerless molding **Pros:** No runner scrap, short cycle, good pack **Cons:** Gate vestige or blemish, needs temperature control, not for heat sensitive resins without care **Degate:** None (runnerless) **Gate:** Valve gate **Desc:** Hot runner nozzle with a pin that opens and closes the gate **Best:** Cosmetic parts, large parts, sequential valve gating **Pros:** Clean gate mark, control of open and close timing, helps weld line control **Cons:** Higher tool cost, more maintenance, more components **Degate:** None (runnerless) **Notes:** Gate type and location are best decided with flow simulation and the tool designer. This table gives general guidance and does not replace a design review. ## Content **Intro:** The gate controls how plastic enters the cavity, so gate type changes cosmetics, stress, warpage and cycle time. This table compares common gate types and where each is normally used, so you can discuss options with your toolmaker. **Sections:** #### How to pick a gate **Body:** Start with the part shape and where a gate mark is acceptable. A cosmetic outer surface needs a hidden or very small gate, a flat panel may need a fan or film gate for even flow, and a round hollow part often uses a diaphragm or ring gate. Then consider volume and automation: if you need unattended running, a submarine or hot runner gate removes the gate without manual work. Finally check resin: brittle or glass-filled materials can break at a submarine gate and may need an edge or hot tip gate. **Bullets:** - Gate near the thickest section so pack reaches it - Aim the gate at a wall to avoid jetting - Keep flow length within what the resin and wall can fill #### Size, shear and freeze time **Body:** Gate size sets shear rate and freeze time. A gate that is too small raises shear, causes blush and degrades the melt, while a gate that is too large leaves a large vestige and may not freeze quickly enough to limit pack. The gate should freeze after the part is packed but before the cycle is wasted waiting. Gate seal studies, which increase hold time and weigh the part until weight stops rising, show exactly when the gate freezes. #### Hot runner and valve gates **Body:** Hot runner systems keep plastic molten up to the gate, which removes runner scrap and shortens cycle. Valve gates add a mechanical pin for clean gate marks and sequential filling, helpful for large parts and weld line control. They cost more and add maintenance, so they pay back mainly in high volume or cosmetic work. Watch for leaking, thermocouple faults and heater failures, and log these in your maintenance system. #### Common mistakes **Body:** Typical errors include placing the gate where the part will be loaded and warping, gating a thin wall into a thick section so the thick area has no pack, and ignoring where weld lines will form. Changing gate size later by welding and re-cutting steel is possible but must be tracked. Document gate type, size and location on the tool drawing and the process sheet so repairs return it to the qualified condition. **Cta:** If you want gate seal, scrap and cycle data from the press tied to the tool record in your ERP, Netray can help you build that reporting inside your own environment. **Faq:** #### Which gate type avoids a visible gate mark? **Answer:** Submarine and cashew gates on a hidden surface, and hot runner valve gates, leave small or hidden marks. The right choice depends on the part geometry, the resin and acceptable cosmetic standards. #### What is the purpose of a tab gate? **Answer:** A tab gate moves the high shear and jetting at the gate away from the functional surface of the part. The tab is removed after molding, which adds a trimming step but improves surface quality and reduces stress. #### How do I know when the gate has frozen? **Answer:** Run a gate seal study: increase hold time in steps and weigh the parts. When part weight stops increasing, the gate has frozen. Use a hold time slightly above that point to avoid wasting cycle time. #### Why choose a three-plate mold? **Answer:** Three-plate molds allow pin-point gating almost anywhere on the part surface and automatic separation of the runner. They cost more and generate runner scrap, so teams compare them with hot runners. ## Search terms injection mold gate types, submarine gate vs edge gate, pin point gate three plate mold, valve gate hot runner, fan gate vs film gate, gate location injection molding, tab gate purpose, diaphragm gate ring gate --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json