Blow Molds for Plastics
Blow Mold Company

Tools & Information


Conversion Chart

Blow Molding Glossary

AIR DEFLECTOR - Thin sheet metal pieces placed on the inside edge of molds so that sssssthe air exhaust from one set of molds does not interfere with the parison dropping to the other set of cavities. They are place on the right side of the left mold and the left side of the right mold.

BACKPLATE - The plate that goes on the back of the mold. It is used to make up thickness, transfer water, and provide mounting to the platens.

BACKUP PLUGS - Plugs put behind the pins and bushings to provide filler so that the pins and bushings are not pushed in from the face of mold.

BASE CORNER RADIUS - The radius at the bottom of the bottle that transitions from the tail to the bottle sides.

BASE INSERT - Also called the tails, this forms the bottom of the bottle. It is usually crowned and has the pushup cut into it.

BEAD - The bead is in the neck. It is below the threads and is a ring on the bottle (or a groove on the neck insert).

BORE - The "E" diameter of the neck. It frequently extends into the mold body at the top of mold. If it extends into the mold body it is called the match diameter.

CAPACITY - The volume that the mold cavity will hold. It is measured to the neck insert break unless otherwise stated.

CAVITY - The actual machined bottle shape.

COOLING BLOCKS - A piece that is installed below the tails that cools any excess flash that may be squeezed out of the tail flash pocket.

CROWN - Also called the push-up it is the portion of the tail that raised into the bottom of the bottle. It is there to give the bottle strength and to allow for processing variations that may distort the bottom of the bottle.

CUP STYLE BASE - It is the type of tail on the mold that incorporates the base corner radius into the tail creating a cup effect.

DEEPEST POINT - The longest points on the bottle. It is generally in the base corner radius near the tail it is the points on which the bottle will rest when it is standing.

DETABBER - A mechanical device that removes the tail flash from the bottle prior to the mold opening. There are various types with slides and cams but all have air cylinders that provide the movement and a stripper bar that holds the excess plastic.

DOME - A cavity on the top of the mold that is used to blow the bottle. It is generally used on molds with large diameter necks. In some cases a spin dome is used. This dome is spun with a belt while the neck is spin trimmed.

"E" - The bore of the neck, it is the basic diameter of the neck away from the threads.

ENGRAVING -The process of milling letters,numbers,and symbols using small diameter cutters.

"H" - The height of the neck of the bottle. It generally is measured from the top of the neck to the bead or shoulder of the bottle. A portion of the "H" may be in the mold body. Some customers have their own definition for the "H" dimension that may vary slightly from ours.

HANDLING - See chapter 2 of this manual which describes handing in detail.

INTERRUPTED THREAD - Thread on the neck that is stop and restarted, usually at the parting line. This is most often done when the neck is to be pinched.

KNIFE - A piece used on molds with domes that forms the top of the neck. It is usually steel. It thins the material to allow for easier trimming.

LEFT HAND MOLD - The mold on the left side of a shuttle type machine. The water lines would come out of the mold on the left side.

MATCH DIAMETER - The diameter on the top of the mold body or shoulder insert that matches the bore of the neck.

MOLD BODY - The basic block of material that has the cavity or cavities machined into it.

NECK INSERT - Also called the finish insert, it is the piece that has the neck features machined into it.

OVALIZATION - The necks features are ovalized in the mold to compensate for out of round necks on the bottles.

PANEL CORRECTION - Panel modification of flat panels to compensate for processing distortion. The modification results in flat panels on the bottle.

PARTING LINE - The joint between the pin and bushing side of the mold.

PILLAR POST - Posts on the bottom face of the backplate used to distribute the platen forces if the mold does not cover the center of the platen. They provide a positive stop point on the mold when the pin and bushing half of the molds close together.

PINCH - The part of the mold that pinches the parison, sealing off the parison and allowing the bottle to be blown.

PINCH LAND - The flat surface on the top of the pinch, usually .015 to .020 wide. The pinch land on the pin and bushing half meet and create the actual pinch.

PINCH PLATE - A plate inserted on the face of mold usually made of Beryllium Copper, Steel, or other hard material that has pinch details cut into it. It is used on aluminum molds so that the whole mold does not have to be made from the harder material.

PINCH RELIEF - The flat area outside of the pinch that is relieved to accept the plastic on the outside of the pinch. PINCH SCREWS - Screw used to hold the pinch plate in place.

PLASTIC RELIEF HOLES - Holes on the side of mold on the bushing halves that allow any plastic caught in the pins and bushing to get pushed out of the bushing through the side hole.

PRESS FIT - For our purposes .0005" to .001" diameter smaller that the item that goes into the hole unless specified on the drawing.

PROUD PINCH - Pinch that is above the parting line of the mold. PRY SLOTS - Slots on the parting line of the mold body that are used to pry the mold open.

PUSH PAD - Usually a flat slightly below the main pinch land used to push plastic toward the pinch so that the pinch off seals better in the plastic.

PUSH-UP - The raised, domed up area on the tail, also called the crown.

RECYCLE LOGO - The triangle shaped engraving usually on the bottom of the bottle designating the type of plastic the bottle is made of.

REFERENCE - A clean, square, perpendicular cut made on the side or bottom of a piece made in a known relationship to a feature on the part.

REGISTERS - Used in place of key ways or dowel pins on most molds the register aligns necks or other items to the mold body by use of step cuts on both sides of the parts. The register on the neck would align with a corresponding register on the mold body, keying the neck to the body and not allowing the neck to move with relation to the mold.

RIGHT HAND MOLD - The mold on the right side of a shuttle type machine. The water lines would come out of the mold on the right side.

ROCK CORRECTION - Small feet added to the bottom of the cavity that the bottle actually rests on. These are used so that the bottle does not rock when sitting on a flat surface. This is the deepest point of the tail so the overall height of the bottle is measured from the rock correction to the top of neck.

SHOULDER - The transition area on the bottle from the neck to the body.

SHIPPING STRAPS - Also called safety straps these are straps screwed to the sides of the molds that hold the two halves of the mold together while the mold is being moved.

SLIP FIT - For our purposes .0005" to .001" diameter larger than the item that goes into the hole unless specified on the drawing.

STACK HEIGHT - The overall thickness of the mold when it is closed. This includes mold body, backplate, etc.

STAMPING POCKETS - A .010 deep pocket that contains the stamping. It is done to protect the stamping from being wiped out from future if the area is ground or has something rubbing against it.

STRIKER - Also called and anvil or impacter these are hardened steel pieces that go on the top of the mold that the blow pin rests against during the bottle blowing operation. Strikers come in one, two or four sided varieties and are either pinched or not pinched. The land of the striker makes up part of the "H" and "S" dimension of most bottles.

STRIPPER BAR - Part of the detabber, this bar grabs and removes the flash before the mold opens. It is usually a grooved piece that strips the flash when the air cylinder is activated.

THREAD"T" - The major diameter of the thread on the neck of the bottle. "T"'s are frequently ovalized to compensate for distortion during molding.

T.I.R. - Abbreviation for Total Indicator Reading.

T.S.C. - Abbreviation for Theoretical Sharp Corner.

TAIL POST - The part of the tail that sticks up like a post into the mold body on "post" style tails. The post mold body joint is usually in the just inside the base corner radius.

TIE BAR CLEARANCE - The area that is cut out from the mold to allow clearance for the molding machine tie bars.

TRIM TOOLING - Auxiliary equipment that trims the flash from the bottle after molding. Trim tooling usually consists of transfer tooling which moves the bottles between the trim tooling stations, nests which hold the bottle, and punches which actually cut the flash.

TUNNELS - Areas along the pinch at the base of the bottle that is raised from the bottom of the bottle to allow excess tail flash an area that will not cause the bottle to rock on the flash.

VENTS - Something used to allow air to escape from the cavity, either along the parting line as a peripheral or bar vent, or in the cavity as a pin vent.

VENT PINS - Usually a brass pin that has slots these are pressed into the cavity to allow air to escape from the cavity. These are also used in IML applications.

VENT RELIEF - A relief cut connected to the actual vent that allows the air to escape to the outside of the mold. The vent relief is much larger and deeper than the actual vent.

WATER CHECK - A water pressure test of the mold to make sure the mold does not leak and that water flows throughout the mold.

WEB - The thickness of metal on the mold body at the bottom of the mold. It is usually between .125 and .250 thick. The web at the base of the mold is only on molds with post style bases. The web matches the post height. WIPING - The hand polishing of the molds to remove tool marks.


Conversion Chart

Metric Measures >> US Measures

1 Dram (dr)
.125 Ounces (oz)
1 Cubic Centimeter (cc)
.03 Ounces (oz)
1 Liter (l)
>2.1 Pints (pt)
1 Gram (g)
.035 Ounces (oz)
1 Kilogram (kg)
2.2 Pounds (lb)
1 Millimeter (mm)
.039 Inches (in)


US Measures >> Metric Measures

1 Ounce (oz)
8 Drams (dr)
1 Ounce (oz)
29.57 Cubic Centimeters (cc)
1 Ounce (oz)
29.57 Milliliters (mm)
1 Pint (pt)
.47 Liters (l)
1 Ounce (oz)
28.35 Grams (g)
1 Pound (lb)
.45 Kilograms (kg)
1 Inch (in)
25.4 Millimeters (mm)


Inches >> Millimeters

Inches (in)
Millimeters (mm)