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KLS’sKLS’s

GOGTE INSTITUTE OF TECHNOLOGYGOGTE INSTITUTE OF TECHNOLOGYUDYAMBAG, BELGAUMUDYAMBAG, BELGAUM

HOT RUNNER SYSTEMSHOT RUNNER SYSTEMS

Under the Guidance ofUnder the Guidance ofShri. M. D. DESHPANDE Shri. M. D. DESHPANDE

ProfessorProfessorDepartment Of Mechanical Engineering, GIT.Department Of Mechanical Engineering, GIT.

Submitted bySubmitted byAKASH SHETTANNAVARAKASH SHETTANNAVAR

USN No: 2GI08ME006 USN No: 2GI08ME006

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CONTENTSCONTENTS

1.1. IntroductionIntroduction2.2. What does a hot runner do?What does a hot runner do?3.3. Main benefits of hot runner systemsMain benefits of hot runner systems4.4. Working principleWorking principle5.5. MaterialsMaterials6.6. Merits and DemeritsMerits and Demerits7.7. ReferencesReferences

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1.1.IntroductionIntroductionA hot runner system is an A hot runner system is an

assembly of heated components in assembly of heated components in plastic injection moulds that inject plastic injection moulds that inject plastic in to the cavities of the mould. plastic in to the cavities of the mould. A hot runner system usually includes a A hot runner system usually includes a heated manifold and a number of heated manifold and a number of heated nozzles. Hot runners are fairly heated nozzles. Hot runners are fairly complicated systems as they have to complicated systems as they have to maintain plastic material within them maintain plastic material within them in molten state, while the rest of the in molten state, while the rest of the injection mould is being cooled in injection mould is being cooled in order to solidify the products quickly. order to solidify the products quickly.

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2.What does a hot runner 2.What does a hot runner dodo??• Maintains plastic material in molten

state.

• Hot runner moulds use molten plastic and inject it in to the cavity.

• The ideal hot runner system delivers moulded parts of uniform density, free from runners, flash and gates.

• Thus has taken moulding to whole new level.

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3.3. Main Benefits of Hot Runner Main Benefits of Hot Runner SystemSystem

• Reduces cycle time.

• Eliminates the cold runner that would be scrap or require regrind.

 • Improves part consistency and quality. • Reduced gate mark. • Reduces injection pressure. • Sequential filling and family of parts are made

possible by using valve gates. • Increases process control for fine tuning mould

and part.

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4.Working Principle4.Working Principle

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Selecting a Hot Runner System When selecting a hot runner system, the part section wall, the part shape, and the time required for filling the part are the first considerations, and then gate selection, gate design, material and mould design. Material Category For materials with large percentages of filler (for example>15%) or very low melt flow index, the material classification moves up a grade (, i.e., easy to medium or medium to difficult) Parts with very thin wall sections or very long flow lengths need a larger than normal nozzle and gate to achieve proper filling, this may require increasing the nozzle by one or two series. Gate selection When designing an injection mould, the size and location of the gate is one of the most important considerations for correct moulding of the part. Incorrect gate position can result in uneven filling, over packing and dimensional instability. The most common gate type is direct gating, which offers the simplest construction and high reliability.

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Gate Profile Considerations The gate size ensures a good thermal gate is achieved and minimizes the pressure drop across the gate, while maintaining its structural integrity. The gate size affects the following: •Flow Rate.

•Pressure drop through the system.

•Cycle Time.

•Thermal gate shut off after filling.

•Cosmetic impact of the gate on the part.

•Cooling in the gate area.

Gate Design Considerations When deciding on a specific gate design, the following factors must be considered; •Shot size of the part. •Material to be moulded. •Viscosity. •Additives. •Glass Fibre. •Flame Retardant. •Cosmetic appearance of the gate. •Thickness of part walls. •Longest flow length of the part. •Required cycle time

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5.Materials5.MaterialsA.I.S.IA.I.S.I HRCHRC CC SiSi MnMn CrCr MoMo VV SS PP APPLICATIONAPPLICATION

P-20P-20 48-5048-50 0.350.35 0.20.2 1.31.3 1.81.8 0.150.15 ** 0.040.04 0.030.03 BOLSTERS, BOLSTERS, INSERTSINSERTS

H11H11 50-5250-52 0.360.36 0.90.9 0.30.3 4.54.5 1.11.1 0.250.25 0.030.03 0.030.03 PROBE HEAD & PROBE HEAD & CAVITY CAVITY INSERTSINSERTS

H13H13 50-5250-52 0.370.37 0.90.9 0.50.5 4.84.8 1.21.2 0.90.9 0.030.03 0.030.03 CAVITY CAVITY INSERTSINSERTS

HCHCrHCHCr 58-6058-60 1.81.8 0.20.2 0.10.1 1111 ** 11 ** ** GUIDE PILLAR GUIDE PILLAR &GUIDE &GUIDE BUSHESBUSHES

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Heat Treatment

The process is as followsParts are warmed to 400°C.It is then heated in two stages of 650°C and 850°C (holding time of the parts in the stages depends on the cross section).It is then heated to a hardening temperature of 1000°C.It is then quenched in oil at 550°C-600°C.

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6.Merits6.Merits Material cost saving–no runners to Material cost saving–no runners to

regrind or reprocess.regrind or reprocess. Low cost – least expensive for Low cost – least expensive for

large volume production.large volume production. Smaller machines – reduced shot Smaller machines – reduced shot

volume into runners.volume into runners. Automated processing- runners do Automated processing- runners do

not need to be separated from the not need to be separated from the parts.parts.

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DemeritsDemerits Higher maintenance cost because susceptible to Higher maintenance cost because susceptible to

Break downsBreak downs

LeakagesLeakages

Heating element failureHeating element failure

Wear caused by filling elements Wear caused by filling elements Elaborate temperature control required.Elaborate temperature control required. Higher initial start-up costs than for cold runner Higher initial start-up costs than for cold runner

systems.systems.

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7.7. References www.synventive.com www.hasco.com www.moldmasters.com Elementary Mold Design by R.J.W.PieElementary Mold Design by R.J.W.Pie Spear system Hand book,Spear system Hand book,

Seiki Corporation, Japan.Seiki Corporation, Japan. Hasco standard Hot Runner systems catalog,Hasco standard Hot Runner systems catalog,

Hasco India Pvt Ltd,Germany.Hasco India Pvt Ltd,Germany.

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THANK YOUTHANK YOU