EasyShrink: A Device for Safely Applying Shrink Wrap

Designers: Michael Chao, Ian King, Esther Lee, Shengnan Xiang

Supervising Professor: Larry Bohs

INTRODUCTION

The goal of this project was to create a device that enables employees with disabilities at OE Enterprises, Inc. to safely and reliably apply shrink wrap to vitamin supplement bottles.  EasyShrink physically isolates the heat gun from its user using a wooden insulating box. A metal control box with a push button and knob creates easy activation of the automated turntable for a set time interval. This device empowers employees to perform the shrink wrapping task without fear of injury.

SUMMARY OF IMPACT

Employees at OE have been eager to use EasyShrink because it makes shrink wrapping safe and easy.  “Nobody is afraid of using [the EasyShrink]. Actually, everybody wants to use this,” said James Hurst, an OE staff member who oversees the shrink wrapping task. “This is the best thing. It’s helped us out a lot, and we want another one.” Regardless of size, the device can shrink wrap each bottle within 20 seconds. Since its introduction, the EasyShrink has increased total bottle output from 250 a day to 700 a day.  In addition, multiple employees can perform the task with ease, and a few veterans now work independently without supervision.

TECHNICAL DESCRIPTION

EasyShrink (Figure 1) consists of three key components: a wooden insulating box, a metal controller box, and an automated turntable, all of which mount on a consolidating platform of plywood. The insulating box (13”x8?”x10¾”) isolates the high-temperature Master Appliance heat gun from the user. The heat gun rests on a stabilizing wooden block (3.5”x1.5”x1.5”), and its nozzle protrudes into a 5” long, 2” diameter aluminum heat sleeve. The heat sleeve fits snuggly into an aperture in the box facing the motorized turntable, allowing hot air flow to be directed outside. A hinge on the top of the box allows for insertion and removal of the heat gun. The heat gun’s power cord connects to a 3-prong outlet on the metal controller box (9”x5”x6”). Handles affixed to the box sides make the device easy to lift and transport.

The controller box attaches to the side of the insulating box. On top are a turntable activation button and a timing knob to set the desired time for shrink wrap application. When the user pushes the button, the heat gun and turntable are both activated for the time set by the timing knob. A modified Velleman interval timer provides a one-shot interval adjustable up to 35 sec, and an Omron AC relay powers the heat gun and turntable for that interval.  A main power cable extends from the controller box to a surge protector, providing an emergency switch to shut off the entire system if necessary.

The turntable rests on a rectangular wooden platform. A DC gear motor, rotating at 12.5 RPM, mounts to a wooden box on the platform.  A circular motor mount of 1.5” diameter attaches to an 11” diameter wooden turntable.

Countersunk holes in the turntable allow stabilizing pins to hold different sized bottles upright.  Three circular disks accommodate different bottle sizes. Bottles are wrapped upside-down, so these disks are slightly smaller than the respective bottle lids.  Wrapping upside-down allows all bottles to be wrapped without adjusting the height of the heat gun or turntable. The disks remain centered using protruding screws mounted in the turntable and respective holes on the bottom of each disk. The replacement cost for the device is $230.