Application Ideas & Recommendations

HOW TO SIZE

Performance Ratings
KOR-LOK® load ratings are empirically derived from a range of typical application geometries and mold behaviors. Ratings should be used only with calculations using maximum pressure and projected core area, as they already take into account some limits on preload adjustment and mold geometry, as well as cavity pressure drops, action geometry, typical core lengths, etc.

Preload ratings apply to a well secured stiff mold geometry with a core stroke of 5" or less, core lengths 5" or less, and core areas equal to or greater than core projected area. Basically, the load ratings apply to typical applications where mounting is relatively close to the part. For longer cores, or poor mounting support, it is highly recommended that the next larger unit be considered

PFA application specialists are available to discuss recommendations, based on your particular application and their experience. While form, fit, and function for any particular application is the responsibility of the customer, following PFA recommended sizing has shown to be the best way to ensure optimal success.

Selecting Series Size
Injection pressure (P) for sizing calculations is the peak pressure at the nozzle during the injection cycle, and is a function of the injection screw piston area and ram pressure. Typical Injection nozzle pressures are approximately 10 times the hydraulic ram pressure shown on the molding machine. Easy flow plastics typically run at 800 psi hydraulic x 10 = 8,000 psi, while high temperature plastics or glass fill plastic applications may require 20,000 psi or more. Part geometries and minimum wall thickness strongly affect the required processing pressures and thus have a major impact on the series selection.

Projected core area (A) is the projected area along the axis of movement wetted by plastic, including internal shutoff areas. It may be most closely thought of as the area of a slice through the core perpendicular to the core axis. Calculation of the necessary Preload force becomes:

Minimum Preload Fore Rating (Ibs) = A (sq. in.) X P (psi).

The KOR-LOK® Side-Action System is typically chosen with a rating above this force by some margin. For a free application review please contact PFA, providing complete details, such as Core Projected Area, Core Diameter, Core Length, Stroke, Maximum Injection Pressure, Hydraulic Pressure, Material Type, and 3D Drawings of the core/mold arrangement, if possible.

Stroke to include adjustment
Stroke is primarily determined by the need to clear the core from the part, but practical efforts should be made to simplify overall product selection, mounting, and adjustment. Detailed information on a specific size can be downloaded with the CAD file image on our website under KOR-LOK® > CAD Files

Note that for non-integer strokes, we employ a "Variable E" dimension (see dimensional data), such that a standard rod of the next longer integer stroke is combined with the piston tubes to match the desired stroke. The result is a change in the chart "E" dimension.

During setup, the cylinder is advanced causing cylinder stroke to be reduced by approximately .100". Therefore, approximately 1/8" should be added to the retract amount needed to clear the part. Also ensure the cylinder is allowed to stroke fully for proper sensor operation

Mounting Options –
Bolt C'bore & Parting Line
Use of a mounting flange (RFC/SFC), jam nut (JN), alignment screw (AS), and alignment coupler (AC) [or T-Slot in the core] is standard on nearly every application to allow for proper alignment and preload adjustment of the main unit cylinder.

Mounting distance from the core must account for the variable E dimension for non-integer stroke units. Use of integer stroke units is recommended for ease of design and off the shelf delivery. Flanges can be mounted with counter bored mounting bolts in locations desired by the customer, as long as there is equal coverage around the KOR-LOK®. It is recommended that bolts be located outside the diameter of the jam nut for ease of removal and that flanges be spaced off from the mold to allow KL unit to thread through the flange past the flange face approximately 1/8" (or the mold relieved to allow for preload adjustment).

If mounting the unit on the parting line, use a block to capture one side of the flange in place of the mounting bolts. Call PFA for mounting ideas and information regarding proper mold sequencing for flange capture applications.

High Temperature Seals, Wipers, and Sensor Options
SPDT Relay style front (set-locked-preloaded) and rear (pull) sensors (switches) and cables are included with each KOR-LOK® main unit. Use of the sensors during setup and adjustment assists in verification of proper operation (download PDF). The SWITCHMAX® junction box and cabling is recommended for multiple core applications, crash condition cores, or when cross checking of sensor positions or LED indication is desirable.

High Temperature Seals (VI), Metal Rod Wiper (MW) and some High Temperature Sensor (HTS) options are available for very high temperature plastic and die casting environments. For some applications, insulation between the flange and the mold (or flange cooling) may be needed.

Driving Wedges and Racks
Because the KOR-LOK® generates preload though an internal wedge style force intensifier, wedge applications and rack and pinion designs often limit the ability for the main unit to preload the core face.

For wedge applications, preloading the prime mover is often enough to hold the core in position for successful part production, however the core face itself is often not substantially preloaded. As these applications are often difficult in concept, use of the KOR-LOK® system can provide substantial advantages, however, we recommend careful PFA staff review.

Rack and Pinion applications typically have special challenges with a large preload force applied to the gear teeth. Typically the racks are not sized large enough to handle the forces needed to transmit the preload to the core. Careful review is recommended to determine feasibility.

PFA Application Review
Making the difficult easy and successful is one of the great advantages of the KOR-LOK® Side-Action System and we are proud to back that up with the best in service and support. For best results, please have a PFA application specialist review your selection criteria to help ensure nothing was missed. When it looks like a challenge, our application specialists are on your side to find a way to make the difficult easier. For the most detailed sizing information, product specifications, design suggestions, CAD files, and new product updates, call your application specialist today.