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RFID tags for cart tracking.

RFID tags for cart tracking.

RFID tags for cart tracking.

I would like some feedback from anybody using RFID tags for tracking of assembly carts and parts trolleys in a manufacturing environment.
I am considering using RFID for that purpose.

I am contemplating scanning from about 3-5 meter range while chassis carts pass down the assembly line.

I also will be tracking parts trolleys as they are picked and delivered to various points along the assembly line. These will probably pass through the typical double antenna gateway reader as they are delivered to the line.

I am aware of the many consultants willing to sell their services but I would like some first hand experience of users with this type of equipment.

Thanks for any feedback.

RE: RFID tags for cart tracking.

We have experience implementing RFID tag systems. What types of answers are you looking for?
What is your end goal? track parts? back flush inventory? trigger additional processes? cut down on inventory? cut down on premature process waste?

If you just want to track parts, seems like overkill. If you are really trying to build a cohesive system the integrates flawlessly with in your manufacturing environment, the RFID tag is the least of your problems.

StrykerTECH Engineering Staff
Milwaukee, WI

RE: RFID tags for cart tracking.

I am not tracking parts, I am tracking carts which have a chassis of a skid steer loader, carts with the loader arms, a cab cart and an upper chassis cart. There are also a group of parts trolleys which get delivered to various locations along the assembly line. Those are the carts in assembly but in addition there are carts in the robotic welding cells after the robots complete their process I would like to track the carts as they move from welding to the paint staging process and finally to the paint load stations.

What kind of experience have you had with false reads and the reliability of the various scanners and tags. Did you have an consultant help with installation and software or did you do the work yourself?

Thanks in advance.

RE: RFID tags for cart tracking.

Sorry, I probably should have clarified a little more. Ultimately you are interested in the part not the cart, correct? You are just using the cart as a method to track your parts.

As far as experience, we are the consultant, we create the software, and we can help with installation. Although I think most companies can handle that on their own. As far as scan reliability, the biggest problem is going to be scannin/logging it when you want it to be as oppose to too early or late, especially if you are looking at dwell time. RFID is very reliable as far as scanning/recognizing the tag. Plus you can have some sort of audible feedback to verify a tag has been logged.

What you just described doesn't seem like too big of problem. You want to track where a cart is, how long has been there, and how long it takes to get to another station. How long it takes to get to get through the entire process. . . ect. Plus, Doesn't seem like we are talking about thousands of little parts here, seems like maybe tracking 100-200 large parts daily? or less.

Gathering data isn't going to be the biggest hurdle. Do you want to generate an order? update cycle times? manipulate work rates? backflush inventory? how integrated do you want this into your MRP system? That is where the real software issues come to light, but it is also the biggest area of manufacturing improvement in most cases.

StrykerTECH Engineering Staff
Milwaukee, WI

RE: RFID tags for cart tracking.

Some of the carts are pulled by a drag chain while others are hand pushed. The drag chain runs about 2 feet a minute.

The number of carts will be about 700 per 8 hour shift while the part numbers on the various carts will be about 16,000 part numbers with varying quantities. I will be assigning the specific unit to the RFID tag/cart and associating the various pick lists to a specific range of carts.

An example would be the engine cart which has the engine on the cart and about 75 other part numbers to be assembled to the engine. The parts are unit specific meaning the engine can have air conditioning or heater or no heater equipped. The engine can have a block heater or not. There are varying drive systems associated with ground drive and accessory hydraulic pump options. These parts are picked from a supermarket and the cart delivered to the engine sub-assembly line. This cart is hand pushed along a track through 6 stations and then moved to the main assembly line and the engine installed into the unit.

Currently the ERP system has back flush functionality however a larger problem is replenishment of the supermarkets which could be integrated with cart signaling system.  

RE: RFID tags for cart tracking.

So you are back flushing inventory correctly and timely . . ? But your ERP system is too slow to react to refilling the supermarkets?
You have 16,000 unique part numbers?

So in a nutshell you are looking to track one cart, then you use the position of the cart to trigger when to fill various supermarket points?

Could you use a simple 2 bin system in the supermarket area? when 1 bin is empty you fill it, while using the other bin? I'm sure you ruled that out, but I still am trying to get at handle on what problem you are trying to solve. Inventory for accounting is functioning adequately. So I am guessing supermarket bins are going empty, holding up production. Is this the problem or just a symptom?

StrykerTECH Engineering Staff
Milwaukee, WI

RE: RFID tags for cart tracking.

We build units which travel down a drag chain assembly line. The there are 40 different models going down the main assembly line with optional parts. The main assembly line has 25 stations. There are seven different sub-lines feeding the main assembly line. The sub-lines vary in length from two stations up to eleven stations.

There are parts carts (trolleys) being delivered to four different locations along the main assembly line and to the beginning of each of the seven sub-lines. The mainline trolleys are pinned to the assembly line in front of the chassis cart. The mainline carts travel down the line until the pull-off station and a trolley for the next section of the assembly line is then put in place of the now empty previous trolley.

The trolley process includes picking a group of parts for the specific unit for the specific mainline section or sub-line. Delivering the specific cart to the staging point before the various sub-lines and then inserting the cart in the proper sequence per the mainline sequence.

I am trying to address several issues:
1. Is the proper cart being delivered to the staging point?
2. Is the cart on time for the assemby process?
3. Is the picking process occurring on a timely basis?
4. I would like to verify the sequence of units is being adhered to.

To accomplish these tasks I intend to use an RFID tag on the carts and assigning a specific serialized group of parts onto the RFID tagged cart. The cart would be monitored via RFID scanner as the carts pass by the RFID tag antenna station.

I am looking for users which have experience with RFID tracking systems and get an understanding of performance and reliability from their application.

I would like to ask questions like:
How reliable are the scanner/reader?
Do you have false reads and how big of a problem is it?
Is reading of multiple tags a problem?
What other problems have you encountered with your application?

I have talked with several system integrators and hear 'We can do that.' Which I believe but I would like other peoples input.

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