US (AISI)Inch		EUROPE/(DIN)Metric		LOCAL/Japan(JIS)Metric
Projection	Third angle		First angle		Both
Unit	IN/LB		MM/KG		MM/KG
Moldbase	DME		HASCO		Futaba/LKM
Steel	H13 420 P20 D2	1040 0-1 S-7 A2	1.2344 1.2083 1.2311 1.2739	1.2343 1.1730 1.2510 1.2767	P5 NAK55 NAK80
Standardcomponents	DME		HASCO		Dadio/minglee
KnockoutHoles	7” ,4 x16”, 6 x2 8”		200,100 x 400		200,100 x 400
PipeThread	NPT		MM/BSP		MM/BSP
Locatingring	4.000INCH”		100/110/125MM		100/110/125MM
Spruebushing	R1/2”, R3/4”		R10,R15,R40,90		R10,R15,R40,90
Screw	UNC		MM		MM
Ejection Pins	DME		HASCO		HASCO
Leader pinsBushings	DME		HASCO		HASCO
spring	ASSOCIATE		DAIDO,HASCO		DAIDO,HASCO
Hotspruehotrunner	INCOE,DME,KONA, MOLD-MASTER,YUDO		HASCO,Synventive,Mold-Master		HASCO,Synventive, Mold-Master
Oil cylinder	MILLER/PARKER		PARKER		PARKER
Gear/rack	DP		“Module” – MM		“Module” – MM

2.Standard Components:

 

3.The class of injection molds:

There are five categories in  SPI-SPE standard:

3.1 SPI CLASS 101 MOLD– 1 million cycles;

Built for extremely high production. This is the highest priced mold and is made with only the highest quality materials.

a. Detailed mold design required.

b. Mold base to be minimum hardness of 280 BHN.

c. Molding surfaces (cavities & cores) must be hardened to a minimum 50 R/C range. All other functional details, such as slides, heel blocks, ect. should also be of hardened tool steels.

d. Ejection should be guided.

e. Slides must have wear plates.

f. Temperature control provisions to be in cavities, cores and slide cores whenever possible.

g. Electroless nickel plating of all water channels is recommended. This greatly inhibits the chance of rust and makes it easy to clear sediment from plugged lines.

3.2 SPI CLASS 102 MOLD – 500k cycles

Medium to high production.Mold good for abrasive materials and/or parts requiring close tolerances.This is a high quality mold. Fairly high priced.

a. Detailed mold design recommended.

b. Mold base to be minimum hardness of 280 BHN.

c. Molding surfaces ( cavities and cores) must be hardened to a minimum of 48 R/C range. All other functional details, such as slides, heel blocks, gibs, wedge blocks, ect. should be heat-treated likewise.

d. Temperature control provisions to be directly in cavities, cores, and slide

e. Parting line locks are recommended on all molds.

f. The following items may or may not be required depending on the ultimate production quantities anticipated. It is recommended that those items desired be checked and made a firm requirement for quoting purposes:

i. Guided ejection

ii. Slide wear plates

iii. Electroless nickel plated water channels

iv. Plated cavities

3.3  SPI CLASS 103 MOLD – 250k cycles;

Medium priced mold. This is a popular mold for low to medium production needs. Most common price range.

a. Detailed mold design recommended.

b. Mold base to be minimum hardness of 165 BHN.

c. Molding surfaces (cavities and cores) must be hardened to a minimum of BHN range. All other s range functional details such as slides, heels blocks, gibs, wedge blocks, ect. should also be of hardened tool steels.

d. All other extras are optional.

3.4  SPI CLASS 104 MOLD – 10k cycles

Low production mold. Used for limited production, preferably with non-abrasive materials. Low to moderate price range.

a. Mold design recommended.

b. Mold base can be mild steel or aluminum.

c. Cavities can be aluminum, mild steel or any other agreed upon metal.

d. All other extras are optional.

3.5  Class 105:less than 500,prototype production or test

It may be constructed from cast material or epoxy or other material offering enough strength.

4.Types of Injection Mold:

4.1 Two Plate Mold:

It is also called single parting surface mold, one of the simplest injection mold .The mold maily includes two half: the stationary half and movable half,which forming the shape of molded plastic part.The sprue and main runner stay with A half, sub runner lies on the parting surface,molded part and runner material kept with B half and then were ejected by ejection system on the B half.(figure 1.1). All other type mold has the common parts with two plate mold.

4.2 Three Plate Mold( Pin-Point Gate Mold):

This kind of mold includes two parting surfaces which divide the mold into three half:A half,B half and stripper plate. It is used when the part can not be gated at the out peripheral and has more complicated structure:the parting sequence is controlled by stripper bolt or other devices:such as DME latch-lock.(Figure1. 2).

4.3  Hot Runner Mold(including hot sprue)

The melt can not freezed with the aide of heating device and there is no runner reground.It is also called runnerless mold. Primary advantages of hot runner molding include:

• Materials cost savings – no runner to regrind or reprocess
• Least expensive cost / piece
• Reduction of energy costs
• Shorter, faster cycle times – no runners to cool
• Smaller machines – reduced shot volume into runners
• Automated processing ?runners do not need demolding
• Gates at the best position for economical design
• Elimination of runners means
• No runners to remove or regrind
• Reduces the possibility of contamination
• Lower injection pressures
• Lower clamping pressure
• Consistent heat within the cavity
• Shorter cooling time
• Shot size reduced
• Cleaner molding process
• Eliminates nozzle freeze

Resin could be used for hot runner molding: PE, PE, ABS, POM, PC, HIPS and PS. The frequently structures  used in our workshop: with a hot sprue(no manifold), with hot manifold and  insulate runner mold:

4.4  Throughly harden(46HRC or Above)

Cavity,core or other moving part must be harden to a minimum of 46 HRC by heat treatment such as Quenching,Carbonitriding, Nitriding.:.

Steel used for this kind of mold: H13,420,S7,A2,D2,O1.

4.5 Pre-hardened(44HRC or Below)

4.5 Pre-hardened(44HRC or Below)

Steel used for Cavity,core or other moving parties is preharden and no other heat treatment needed.

The most often used  steel: P20(1.2312/1.2738/1.2711),1045, 420H ,NAK80,AL7075,BeCu.

It is a common practices that the harden mold must be inserted,that is the cavity and core has different steel with the mold base;On the contrary,the cavity shape of preharden mold often directly machined from the A plate.

4.6.Terminology Used in Moldbuilding:

4.6.1 Undercut

Th part draft direction is different with mold opening direction,such as through  hole on the part side wall,snap structure, and undercut releasing system needed to mold this kind of part.

Two kind of mechanism often used for undercut releasing:

a)Slide:for external underut

b)lifter:for internal undercut

4.6.2. Floating cores

Floating core used for two condition:

A)Part has  a thin and  long shape with a small draft angle.

B)Part has a small undercut distance and slide or lifter could not be used.

It works as following:

1.The floating core and the part was ejected together,

2.the undercut was forced deformaed to release from core insert.

Special care must be taken :the stroke limit and return of floating core.

The floating core could be square or cylinder. One typical example was shown below, The space for undercut deformation could be get after first ejection,then the part could be ejected by ejection pins:

4.6.3.Floating A plate

It works as follow:

The spring loaded A plate opens first( at PL1),the undercut releasing system retract at the same time,when the stripper bolt reach its end stroke,mold opening at PL2 takes place.

It is often used when under cut releasing system located on the cavity side.