Injection Molding EPDM Rubber Insert Molding

Elastimold, Inc.

Albuquerque, New Mexico

Before Using Sensonetics:

"We had a high level of rejects, and had to adjust machine injection pressures from 3-6 times each shift, on each of our DESMA 4-Station Rotary and Lewis Vertical Machines, to control the Fill/Flash Balance to minimize rejects,"

After using Sensonetics Nozzle Pressure Transducers For Melt Pressure Control:

"The machines run without rejects and without adjustments for weeks at a time. We only make about 3 very minor adjustments in 10 weeks. We have installed 15 to date, and will order 50 more units for this plant, plus additional quantities for the Ackettstown, New Jersey and Asian Plants."

Annual Savings: Over $30,000 Per Machine

Pay Back:  1.5 Months

George Havlena
 

Measuring Pressure Fluctations in the Nozzle Area of a Hydraulic Pressure Transducer Controlled Machine

Machine: 250 Ton Hydraulic Machine with pressure multiplier factor of 10, Operating with a hydraulic Pressure Transducer at 2,000 psi max, for a theoretica; Ppeak-max of 20,000 psi

Monitor: Silicon on Sapphire Nozzle Pressure and Temperature Sensor with Nicolet Process Monitor

Mold: 32 Cavity Cap/Closure Mold, Molding HDPE Resin, 1.5 Grams/Part

Monitored Conditions:
 

Conclusions:

This example shows that excessive pressure variations of 420 psi are normally encountered at the nozzle with traditional hydraulic transducer control. This machine can benefit from Silicon on Sapphire Nozzle Melt Pressure Control to 20-30 Psi Accompanied by a significant reduction in rejects with less routine machine adjustments.

Why measuring Nozzle Pressure and Temperature is important:

1. Defines conditions for the uniformity of the plastic melt.

2. Peak and pack pressures will control the shot weight.

3. Quality depends on melt pressure repeatability and temperature uniformity.

4. Hydraulic pressure is not a good indication of nozzle pressure.

5. Barrel temperatures are not a good indicator of melt temperature.

6. Alerts the operator to an out of control condition.

7. LVDT position transducers cannot directly control the shot weight.

Requirements for Injection Molding Data Acquisition Systems:

1. Signal Reception of 0-10 vdc.

2. Windows Operating System.

3. 2-8 channels of Acquisition.

4. 1-4 mS Sampling Rate of Melt Pressure

5. 100-500 mS Sampling Rate for Melt Temperature

6. Statistical Data Analysis and SPC

7. Pressure Cycle Plot Every 1-10 Shots

8. Portability for Pressure Side Usage

9. No Special Sensors or Hardware

10. Functionality vs Objectives
 
 

Injection Machine Control Systems