Increasing Productivity in the Injection Molding Process

Part of calculating the productivity in an injection molding operation is to figure out the maximum number of items you’d be able to produce if everything worked perfectly. Unfortunately, “everything working perfectly” is not something you often see in manufacturing. How can you get closer to that ideal number? One answer lies in a little sensor which can monitor environmental conditions vital to your operation. With it you can reduce your machine downtime and the amount of scrap you produce.

Condition monitoring sensors seem to be taking the automation world by storm. These sensors take various measurements including temperature, ambient pressure, relative humidity, and vibration. They report the data digitally, which makes it easy to track performance. What used to require several sensors now requires only one.

Monitor humidity in plastic granule drying process

Following the plastic injection molding process from beginning to end we can see the usefulness of this one sensor. Plastic granules need to be dried before they go into the machine. If the moisture level is too high, it can cause splay marks to show up on the final product, which then has to be scrapped. This can be costly and can extend lead times if it is not detected early on. The condition monitoring sensor can track ambient humidity so you can stop that problem in its tracks before it creates waste and increases overhead.

Monitor temperature in the injection molding process

One of the biggest variables to any injection molding process is temperature. Some common temperature-related issues in injection molding include blistering, burn marks, degradation of the polymer used, stringiness, and warping. These are caused by temperature variations that cause the resin to be too hot or too cold. Condition monitoring sensors can detect swings in temperature to prevent products having to be scrapped.

Monitor vibration to detect mechanical wear

It’s clear that condition monitoring sensors can helpfully measure environmental factors, but what about mechanical wear? Vibration sensors can monitor mechanical wear on bearings, linear drives, gearboxes and much more by plotting vibration data. It’s even more effective if they measure vibration on more than one axis so you can see the direction of vibration and not just the overall amount. This way you can be proactive and plan your maintenance in advance instead of being in a constant reactive state, trying to patch problems as they come up. Using vibration data gathered by a condition monitoring sensor, you can avoid the costly consequences of unscheduled downtime.

In conclusion there are many different applications that condition monitoring sensors can be used for in injection molding operations. By tracking a variety of different measurements including vibration, temperature, and humidity, you will be able to improve the efficiency and productivity of your entire operation by using this one compact sensor. It provides a low-cost solution so that you can reduce the scrap that is cutting into your profits. And reduce the amount of downtime that causes so many unnecessary headaches. Put these smart sensors to work for you.

Harsh Industrial Environments Challenge Plant Operators

Most industrial processes do not take place in a climate-controlled laboratory or clean room environment. Real-world industrial activity generates or takes place under harsh conditions that can damage or shorten the life expectancy of equipment, especially electronic sensors.

A cross-section of industrial users was surveyed about operating conditions in their facilities. The responses revealed that plant operators are challenged by a variety of difficult environmental factors, the biggest being heat, dust/dirt/water contamination, vibration, and extreme temperature swings.

linearpositionsensorinfographic

Over one-third of the industrial users surveyed reported that premature sensor failure is a problem in their operations. That is a surprisingly high percentage and something that needs to be addressed to restore lost productivity and maintain long-term competitiveness.

Many heavy industries are dependent on automated hydraulic cylinders to move and control large loads precisely. The cylinder position sensors are often subjected to damaging environmental conditions that shorten their life expectancy, leading to premature failure.

Fortunately, there are measures that can be taken to reduce or eliminate the occurrence of sensor-related downtime. Help is available in the form of a free white paper from Balluff called “Improving the Reliability of Hydraulic Cylinder Position Sensors”.

To learn more about this topic you can also visit www.balluff.us.

Sensor Reliability in Steel Production

01_SteelIn any continuous manufacturing process such as steel production, increased throughput is the path to higher profits through maximum utilization of fixed capital investments. In order to achieve increased throughput, more sophisticated control systems are being deployed. These systems enable ever-higher levels of automation but can present new challenges in terms of managing system reliability. Maintenance of profit margins depends on the line remaining in production with minimal unexpected downtime.

It is essential that control components, such as sensors, be selected in accordance with the rigorous demands of steel industry applications. Standard sensors intended for use in more benign manufacturing environments are often not suitable for the steel industry and may not deliver dependable service life.

When specifying sensors for steel production applications, some environmental conditions to consider include:

Heat

High-temperature M30 proximity sensor.
High-temperature M30 proximity sensor.

High temperatures exist in many areas of the steel-making process, such as the coke oven battery, blast furnace, electric arc furnace, oxygen converter, continuous casting line, and hot rolling line. Electronic components are stressed by elevated temperatures and can fail at much higher rates than they would at room temperature. Heat can affect sensors through conduction (direct transfer from the mounting), convection (circulating hot air), or radiation (line-of-sight infrared heating at a distance). The first strategy is to install sensors in ways that minimize exposure to these three thermal mechanisms. The second line of defense is to select sensors with extended temperature ratings. Many standard sensors can operate up to 185° F (85° C) but high temperature versions can operate to 212° F (100° C) or higher. Extreme temperature sensors can operate to 320° F (160° C) or even 356° F (180° C).

Don’t forget to consider the temperature rating of any quick-disconnect cables that will be used with the sensors. Many standard cable materials will melt or break down quickly at higher temperatures. Fiberglass-jacketed cables, for example, are rated to 752° F (400° C).

Shock and Vibration

Hydraulic cylinder position sensor rated at 150 G shock.
Hydraulic cylinder position sensor rated at 150 G shock.

Steel making involves large forces and heavy loads that generate substantial amounts of shock under normal and/or abnormal conditions. Vibration is also ever-present from motors, rollers, and moving materials. As with heat, look for sensors with enhanced specifications for shock and vibration. For sensors with fixed mountings, look for shock ratings of at least 30 G. For sensors mounted to equipment that is moving (for example, position sensors on hydraulic cylinders), consider sensors with shock ratings of 100 to 150 G. For vibration, the statement of specifications can vary. For example, it may be stated as a frequency and amplitude, such as 55 Hz @ 1 mm or as acceleration over a frequency range, such as 20 G from 10…2000 Hz.

Don’t forget that the quick-disconnect connector can sometimes be a vulnerability under severe shock. Combat broken connectors with so-called “pigtail” or “inline” connectors that have a flexible cable coming out of the sensor that goes to a quick-disconnect a few inches or feet away.

Mechanical Impact

Steelface proximity sensors bunkered in protective mounting.
Proximity sensor bunkered in a protective mounting block.

The best way to protect sensors from mechanical impact is to install them in protective mounting brackets (a.k.a. “bunker blocks”) or to provide heavy-duty covers over them. When direct contact with the sensor cannot be avoided, choose sensors specifically designed to handle impact.

Another strategy is to use remote sensor actuation to detect objects without making physical contact with the sensor itself.

Corrosion and Liquid Ingress

In areas with water spray and steam, such as the scale cracker on a hot strip line, corrosion and liquid ingress can lead to sensor failure. Look for stainless steel construction (aluminum can corrode) and enhanced ingress protection ratings such as IP68 or IP69K.

When All Else Fails…Rapid Replacement

Quick-change prox mounts for proximity sensors.
Quick-change prox mounts for proximity sensors.

If and when a sensor failure inevitably occurs, choose products and accessories that can minimize the downtime by speeding up the time required for replacement.

Strategies include quick-change sensor mounts, rapid-replacement sensor modules, and redundant sensor outputs.

In the case of redundant sensor outputs, if the primary output fails, the system can continue to operate from the secondary or even tertiary output.

You can learn more about sensing solutions for the Steel Industry in Balluff’s industry brochure.