Motion Control Shades of Grey

by Brian Taylor
Applications Engineering Manager

Introduction

Since the beginning of my career in motion control, certain application considerations have made me pause for thought, and also caused great confusion among my peers. These could affectionately be referred to as the “grey” areas of motion control. Where no Controls Engineer really wants to go, but alas, in their design efforts, they must.  Grey application issues include such heavily debated topics as:

  • closed loop vs. open loop vs. hybrid technology
  • sinking vs. sourcing I/O
  • load to rotor inertia ratio

You get the idea. Like the mysteries surrounding Stonehenge, crop circles, who shot JFK, and what really would any self-respecting individual actually do for a Klondike bar – here we will tackle the elusive IP rating for industrial motors and what it means for your application. Specifically addressing IP65 and what it does and doesn’t mean, for an understanding of how to correctly apply these products.

IP ratings: the true letter of the law!

There are so many opinions about the meaning of IP ratings that it is, in a word, frustrating. The actual definitions are very black and white. Published by the International Electrotechnical Commission (IEC), and detailed by IEC standard 60529, IP ratings/Ingress Protection Ratings or International Protection markings classify and rate the degree of protection provided against intrusion (body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures.
An IP rating indicates the protection level provided by the enclosure of a device. The ratings are two, or sometimes three, numbers indicating protection levels.

IP number: Indicates protection from:

  • 1st position solid objects or materials
  • 2nd position liquids (water)
  • 3rd position mechanical impacts (commonly omitted as not part of IEC 60529)

Example: IP65 denotes protection levels from solid objects by the “6”, and liquids by the “5”.

The range of IP rating levels are defined in the following tables.

IP 1st number — Denotes protection from solids

Level Object size protected against Effective against
0 No protection against contact and ingress of objects
1 >50mm Any large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part
2 >12.5mm Fingers or similar objects
3 >2.5mm Tools, thick wires, etc.
4 >1mm Most wires, screws, etc.
5 Dust protected Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment, complete protection against contact (dust proof)
6 Dust tight No ingress of dust, complete protection against contact (dust tight)

Table 1: IP rating first number designations

IP 2nd number — Denotes protection from liquids

Level Protected against Testing or >Details<>
0 Not protected
1 Dripping water Dripping water (vertically falling drops) shall have no harmful effect Test duration 10 minutes. Water equivalent to 1mm rainfall per minute
2 Dripping water when tilted up to 15° Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position Test duration 10 minutes. Water equivalent to 3mm rainfall per minute
3 Spraying water Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect Test duration 5 minutes. Water volume: 0.7 liters per minute. Pressure 80-100kPa
4 Splashing of water Water splashing against the enclosure from any direction shall have not harmful effect Test duration: 5 minutes. Water volume: 10 liters per minute. Pressure 80-100kPa
5 Water jets Water projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects Test duration: at least 3 minutes.
Water volume: 12.5 liters per minute. Pressure: 30kPa at distance of 3m
6 Powerful water jets Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects Test duration: at least 3 minutes.
Water volume: 100 liters per minute. Pressure: 100kPa at distance of 3m
7 Immersion up to 1m Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time Test duration: 30 minutes. Up to 1m of submersion (condensed description)
8 Immersion beyond 1m The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects Test duration: continuous immersion in water. Depth specified by manufacturer, generally up to 3m

What IP means for my application

As defined in the preceding rating tables, an IP65 motor is considered dust tight. It is also sealed against water projected from any direction from a distance of 3 meters through 6.3mm water jet nozzles for a duration of at least 3 minutes with pressure not exceeding 30 kPa. Wow! Could they have nailed this down any further?

Reviewing your application needs, how do you decide if IP65 is an adequate protection level?

You will want to consider if the motor will:

  • be used outdoors?
  • need to be fully submerged?
  • be subjected to wash down conditions?

Contrary to some opinions, or a general lack of understanding, the fact is that an IP65 specification does not certify a product operate in any of these conditions.

IP65 rated motors:

  • are not certified for outdoor applications, without additional protection from the elements.
  • are not fully water submersible.
  • are not food grade, with wash-down requirements.

What applications can be solved with IP65 motors? The market space is wide open, provided user’s keep in mind the things IP65 is not.

Integrated motors with IP65 rating

Integrated motors, such as the Lexium MDrive® product line, offer numerous benefits for a wide variety of applications. Combining motor/drive/controller/IO/encoder/closed-loop performance can simplify integration and maintenance, improve efficiency, increase profitability and reduce time to market.

Now, with the newly released IP65 Lexium MDrive products, machine builders have the added advantage of using integrated motors in applications with tough environmental challenges. IP65 LMD products include sealed M12 industrial connectors for power, communications and I/O interface. Custom gaskets seal both the electronics housing and motor, excluding the shaft. The motor is also sealed inside and out with a coating on every surface that could potentially rust.

This type of design is very cost effective for applications in tough environments, whether due to particulates in the air causing contamination (dust, dirt, material chips due to machining, etc.) or process fluids adding moisture. Examples of suitable applications for IP65 Lexium MDrive products include:

  • Packaging applications where various materials are being conveyed.
  • Form, fill, and seal machines where product is being dispensed and sealed.
  • Liquid dispensing and pumping applications in medical devices and life science.
  • Printing and labeling machines, especially barcode and 2D label applications for track and traceability in the medical device and life science areas.
  • 3D printing systems.
  • Machine tool opportunities that could include water jet cutting, laser cutting, tool changers, etc.
  • Assembly and test systems with three and four axis pick and place gantry.
  • Hydraulic and pneumatic cylinder replacement.

Testing to ensure IP65 protection

Understanding the IP rating standard, and specifically getting the picture with respect to IP65, we now know the test criteria a motor must meet. An independent, qualified testing facility places a motor in a sealed chamber filled with blowing fine powder ensuring it is dust tight. In another chamber, 12.5mm nozzles are positioned at a distance of 3 meters to hit the motor from all directions with powerful water jets, not exceeding 100 kPa, for 3 minutes. Passing these tests, the motor is certified and we are good.

Not so fast! This is the test criteria per the IEC standard. However, we completely understand the real world and go quite a bit farther in our Lexium MDrive testing procedures.

In addition to the IEC standard testing for IP65 certification, our own team of quality engineers continues subjecting products in extreme life testing conditions. And, while IP65-rated products are now being offered as standard products, for the past decade thousands of sealed MDrive custom products have been put into use around the globe. The result is true real world quality validation.

Let’s review!

In the lines above we have covered what IP ratings mean for protection levels and testing criteria. We have also, more importantly, covered what ratings do not mean in the case of IP65.

Applying an IP-rated motor in a system is no different than applying a non IP-rated motor, as both require the correct fit for the application to operate successfully. IP ratings do not negate the need for consideration of the environment in which the device will be applied, including the possibility of additional protection.

Exercising their grey matter to understand IP ratings, engineers can make intelligent design decisions. Good decisions, such as selecting appropriately rated devices, result in applications operating as expected in specified environmental conditions.

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