Posted on

Avoid Downtime in Metal Forming With Inductive & Photoelectric Sensors

Industrial sensor technology revolutionized how part placement and object detection are performed in metal forming applications. Inductive proximity sensors came into standard use in the industry in the 1960s as the first non-contact sensor that could detect ferrous and nonferrous metals. Photoelectric sensors detect objects at greater distances. Used together in a stamping environment, these sensors can decrease the possibility of missing material or incorrect placement that can result in a die crash and expensive downtime.

Inductive sensors

In an industrial die press, inductive sensors are placed on the bottom and top of the dies to detect the sheet metal for stamping. The small sensing range of inductive sensors allows operators to confirm that the sheet metal is correctly in place and aligned to ensure that the stamping process creates as little scrap as possible.

In addition, installing barrel-style proximity sensors so that their sensing face is flush with the die structure will confirm the creation of the proper shape. The sensors in place at the correct angles within the die will trigger when the die presses the sheet metal into place. The information these sensors gather within the press effectively make the process visible to operators. Inductive sensors can also detect the direction of scrap material as it is being removed and the movement of finished products.

Photoelectric sensors

Photoelectric sensors in metal forming have two main functions. The first function is part presence, such as confirming that only a single sheet of metal loads into the die, also known as double-blank detection. Doing this requires placing a distance-sensing photoelectric sensor at the entry-way to the die. By measuring the distance to the sheet metal, the sensor can detect the accidental entry of two or more sheets in the press. Running the press with multiple metal sheets can damage the die form and the sensors installed in the die, resulting in expensive downtime while repairing or replacing the damaged parts.

The second typical function of photoelectric sensors verifies the movement of the part out of the press. A photoelectric light grid in place just outside the exit of the press can confirm the movement of material out before the next sheet enters into the press. Additionally, an optical window in place where parts move out will count the parts as they drop into a dunnage bin. These automated verification steps help ensure that stamping processes can move at high speeds with high accuracy.

These examples offer a brief overview of the sensors you mostly commonly find in use in a die press. The exact sensors are specific to the presses and the processes in use by different manufacturers, and the technology the stamping industry uses is constantly changing as it advances. So, as with all industrial automation, selecting the most suitable sensor comes down to the requirements of the individual application.

Posted on

Why In-Die sensing is a must

Metalforming suppliers are facing unprecedented challenges in today’s marketplace. As capital becomes scarce, and competition for business increases, the impact of a die crash or production run of bad parts could make the difference in whether they survive. Companies must protect their most critical assets, the presses and dies. Presses, dies, and various press room automation systems are the lifeblood of the supplier, and their costs can run into multiple millions of dollars in capital investment.

Sensor-driven error-proofing and die protection programs reduce downtime, ensure production is maximized, and prevent costly capital equipment repairs. Sensor implementation can prevent most die crashes and defective parts production if utilized correctly.

The vast majority of expensive press and die damage occurs due to failure to implement or the misapplication of sensing devices through a die protection program. There is a relatively inexpensive way for metal formers to protect their most critical assets in terms of dollar value and revenue creation. Stamping companies need to focus on two main areas to reduce costly repairs and production:

Feed-in and feed-through: You have to ensure the metal is in the press before the start of the cycle, and that it is feeding through properly. Once the cycle has completed, you must make sure the finished part is out of the stamping area. The type of stamping you do will determine the various points where you will need to incorporate sensors.

Part and slug ejection: During the stamping process, scrap material will be left that needs to be removed before the next cycle. Failure to ensure this will leave material inside the press, which can affect product quality or cause significant damage to the press, die, or both.

There are multiple additional processes within the press operation that can improve overall operational efficiency, but the two above should be the first steps toward implementing a successful program.

Multiple sensing devices can help you meet these requirements as well as a variety of suppliers and options you can choose from. It is essential that your personnel are trained on the various sensor technologies, and you are aligned with a supplier that understands the industry, your processes, and the variety of dies and materials you produce.

Many suppliers can provide you with sensing parts, but only a few are industry experts and can serve as both a consultant and parts supplier. You may need to invest a little more to get the expertise necessary to implement a sensing program upfront. Still, it will pay dividends for years to come if you focus upfront on the products that will reduce the downtime related to premature component failure or misapplication of sensor components.

Also, since most suppliers outsource the design and build of their dies, it is critical that your sensor solution partner is involved in new die design, with both your internal team as well as your die supplier. In addition, successful die protection programs entail rigid specifications for die sensing to help reduce their spare parts footprint and maximize the performance of their sensing devices.