There are a wide variety of plastics used in industry today, but only a few meet the demands and requirements for packaging cosmetics, some of which include PET, ABS, PCR and others. Regardless of which plastic material a company chooses to employ, the most important component might not be the cosmetic case itself. Functionality often plays an even more important role than aesthetics. We’re talking about the mechanism used to open and close the case: the hinge. 

There are a number of methods available to provide the hinge on cosmetic cases, such as snap-on or concealed hinges, butt hinges, and Solid Pin hinges, which have their own challenges. For example, a leading cosmetics packaging company of high-end products used two Solid Pins in their styrene case. The two pins caused the case to squeak when opened and closed. This was because the pins relied on deformation of the plastic for retention, which stressed the material and caused the noise. In addition, the holes had to be misaligned in order to keep the Solid Pins in place. Angular pressure caused by the misalignment along with the solid pins bending, also contributed to the squeaking. 

The cosmetics packaging company looked for a new method that would allow multiple opens and closings without making a sound. After some analysis, the company chose to make minimal adjustments to their cases and incorporate SPIROL® Series 550 Cosmetic Coiled Pins as an excellent solution that eliminated the squeaking completely.

Needed Modifications

The plastic molding customer was willing to modify the existing hole size in the case to achieve the proper friction fit for the Coiled Pin. Further, redesigning the hole in the case allowed the company to incorporate a standard Series 550 Cosmetic Coiled Pin, which also reduced costs by avoiding the need for a custom solution. Rather than misaligning holes in the case, the uniform radial spring force of the Series 550 resulted in a controlled hinge movement. 

Uniform radial spring force allows for controlled hinge movement and hinge quality that remains consistent over time. Controlled hinge movement is achieved with wider tolerances and lower molding costs than when a solid pin or cut wire is used. The inherent design of the Series 550 Cosmetic Coiled Pin allows it to flex and absorb impact preventing premature damage to the hole wall. This feature means the quality of the hinge is maintained throughout the life of the product, preventing the lid from flopping open and spilling the contents.

In the end, the cosmetic company got a product that created a seamless experience for the user where the lid opened and closed smoothly and stayed securely in place. Overall, the company was able to solve its squeaking problem with minor permanent adjustments and save costs as well. 

Manufacturing Efficiency

The use of the SPIROL Series 550 Cosmetic Coiled Pins simplified the design and manufacturing process. For example, the low insertion force and compression of the pin during installation minimized hinge stress and scrap. SPIROL had designed a pin installation system Model HC Horizontal Dual Pin Inserter to dramatically increase production efficiency with minimal operator training. 

The Inserter is lightweight and portable for ease of use and flexibility. The cylinder/driving head modules can be moved in and out with ease, and fixture changes are simple, which enables quick conversion from one assembly to another. Pins are delivered automatically to the installation site, eliminating the need for the operator to touch them during the assembly operation. 

For more information, visit SPIROL.

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