In extrusion blow molding a hollow tube or parison is formed by forcing material between a die and a mandrel. A mold cavity, composed of two halves, closes around the parison, sealing the bottom. Blow pins are inserted into the top of the tube, forming the neck. Compressed air expands the parison to conform against the cold mold cavity walls. When sufficiently cool, the mold opens and the container is removed and trimmed of excess plastic or flash. Flash, a basic characteristic of extrusion blow molding, is formed when the parison is pinched off by the mold. Since plastic resins can be reprocessed, the flash is not wasted but is used as regrind mixed back with virgin material. Wall distribution, thickness and weight can be controlled by parison programming. While the parison is extruded, programming changes in the relation of mandrel and die can be used to shift material from heavier, stronger areas to lighter, weaker areas. This method aids significantly in maximizing container performance and minimizing container weight and cost.
Advantages of Extrusion Blow Molding:
- Low initial mold tooling costs.
- Flexibility of tooling. Molds can accommodate interchangeable neck finishes and body sections.
- Flexibility in production: Neck inner diameters (I.D.) can be easily controlled to varying requirements. Bottle weights are adjustable.
- Container sizes can range from less than 1 oz. to 55 gallons and up.
- Container shape is not restricted by blow-up ratios. Bottles can be long and flat or have handles.
- Wide selection of machine sizes: Molds can be geared to volume requirements.
MJS Packaging offers a unique "Building Block" concept of mold design. A tool can start as a 1 cavity tool and additional cavities can be added over time as requirements grow to run as 2, 3, 4, 6 or 8 cavity molds.
Custom tooling is available to meet all packaging needs 100m to 10mm annual unit requirements. A wide range of molding equipment and technology make possible the custom designing and production of components to fit any range of budget and configuration.
Custom variations to stock bottle tooling include:
- Embossing stock containers through the use of a sleeve.
- Neck rings to provide versatility of closure use, including specialty closure applications.
- Inserts to produce a custom capacity or height by inserting a slug into a stock mold with a stack design.
Custom bottle tooling costs depend entirely upon the application and required production rate:
- A single cavity, extrusion blow mold suitable to produce up to 100M units per year may cost as little as $3000.00.
- An eight cavity, extrusion blow mold with automatic detabbing equipment may cost as much as $25,000 but may generate sufficient cost savings to return the investment within a short period.
MJS Packaging has the know-how and experience to provide the type of custom tooling required to fit your packaging needs. Call 800.915.2262 for a consultation on any potential package. A capable representative will be glad to help you evaluate the molding options which may best fit your product.