All information and opinions presented in this paper are the authors. Design News online did no editing or confirmation of the information provided.
The most critical objective of any automated mechanical system is to keep several different moving parts working together continuously. Failure of an individual component often causes confusion as to which component is ultimately responsible for the failure. The more vendors involved in supplying the components, the more blurred the communication and the more prolonged the solution.
When dealing with automation, one of the most common failures occurs with the energy supply cables or hoses. The cables are subjected to constant cycling at high speeds with small bend radii. They also must have an abrasion-resistant outer jacket, even when two cables are placed directly on top of one another with no separation, and conductors must be configured correctly within the jacket. If the cables do not meet these standards, they will "corkscrew" (deform irrevocably).
Cables will "corkscrew" if not properly selected for specific application parameters as shown below.
As automation speeds and cycles increase with new technology, the threat of corkscrewing increases. Average cables that can manage lower speeds and cycles cannot meet the challenge of faster automation. The cable carrier, which is designed to guide, protect and extend the life of these cables and other conduits, is most often blamed for this failure when, in fact, many crucial factors are involved. The result of the failure, regardless of its source, is downtime, extra costs to repair the problem, and loss of production and subsequent income.
Another potential problem is the deformation and/or breakage of the carrier crossbars and links from an "overpacked" cable package. Selecting the right cables, the proper cable carrier (both size and type) and the correct peripheral components will avoid these problems and keep the machinery running smoothly through millions of cycles. The more suppliers involved in providing the components that go into this complete carrier system, the more difficult it is to assure the proper choices have been made.
Multiple suppliers also complicate the logistics of the application. Purchasing, expediting, receiving, inventory control, accounting, and assembly are time-consuming and expensive when individual components come from numerous sources. Each vendor may have a different procedure with different release structures and protocol, further complicating the matter.
The solution rests on finding a turnkey solution – one supplier for the entire cable carrier system with the ability to assemble and ship it, ready to install. The ideal vendor must be accountable for all individual components and all workmanship. The supplier must be able to provide cables and hoses, cable carrier, cable separation components, strain relief, termination components, full assembly and harnessing of these components, the facility to handle this harnessing service, and the experience to support the work.
The ideal cable carrier supplier, at left, will provide all elements of the systems carrier, cables and hoses, separation components, strain relief, termination, mounting elements, and harnessing services.
When selecting a single cable carrier system supplier, look for the following criteria:
Cable carrier and "continuous-flex" cable from the same source
Other time and cost-saving services such as regional and worldwide technical support, customized drawings and designs, design assistance tools (i.e. DXF library, design guidance CD’s, technical information online), technical field service within 24 hours, on-site installation, standards classification and certification (i.e. ISO, CE, etc.)
Complete turn-around time is crucial for anyone looking for a cable carrier system. Current technology allows for faster design capability, faster exchange of information and tighter deadlines throughout the design-to-production time. These time constraints apply to all aspects of a project and most often cannot be sacrificed anywhere along the line. Dealing with one vendor who is an expert in all aspects of a carrier system streamlines the process, so look for a knowledgeable vendor who can offer the most complete system in the shortest time.
The most efficient carrier system provider will keep all necessary components in stock for minimal lead times and "just-in-time" delivery. This is almost impossible for carrier manufacturers or cable manufacturers who only develop and sell one aspect of the system.
In order to maximize conduit life and performance, one cable carrier manufacturer developed its own line of flexible cables and air hoses specifically for use in cable carriers. The company’s previous knowledge of cable and hose behavior within various types of cable carriers made this possible.
igus, inc is a cable carrier manufacturer which developed its own line of continuously flexible cables called Chainflex®, shown at left.
Researching, developing and selling two product lines that work together cuts time by eliminating repeat application explanations to more than one vendor, by having the ability to offer compatible cables and carriers quickly and confidently without the need to consult other experts, and by being able to stock large quantities of both products for immediate shipment.
Short lead times are only one aspect of "speedy" service. Much of this speed should occur before the order is even entered. Look for a vendor who offers a 24-hour turn-around time on carrier system quotes. The customer should be given contact options, such as web site forms which can be e-mailed, an 800 number to call, or a quote sheet to be filled in and faxed. Each option should guarantee a complete system quote for simpler applications and an initial quote response for more complicated applications by the end of the next business day.
Also look for peripheral design tools, such as a CD-ROM that assists the potential customer by automatically suggesting a carrier system based on a few key application parameters. This type of "design assistance" program should be educational and easy to use, providing comprehensive background information on the carriers, cables and components that go into composing a system, a full library of specifications and application examples, and clear step-by-step instructions on how to generate a carrier system analysis.
For applications that require on-site visitation to determine he best cable carrier system for the machinery, look for a company that has regional satellite offices, both nationally and globally. The advantage to regional satellites is their sole devotion to cable carrier systems and customers, giving them expertise and time to visit a site at a moment’s notice and make recommendations on the spot. This local contact is also important for direct communication between the customer and the manufacturer. A global network comes into play when an OEM has worldwide locations that require simultaneous delivery of carrier systems or in a widespread retrofit situation.
Traditionally, it is common for the OEM to purchase the cables, hoses, cable carrier, separation, strain relief, mounting accessories, and connectors from different vendors, have them shipped to an independent harnessing house for pre-assembly, receive the assembled unit back for installation, and then send the completed machine along to the end-user.
Now there is a better option. Select a cable carrier manufacturer that offers its own in-house harnessing services, including purchase of any components it does not manufacture itself.
A carrier company that offers full in-house harnessing services will save the customer valuable time.
This will eliminate unnecessary time spent by the customer gathering components from different vendors, and streamline shipping and communication. Product knowledge on the part of the carrier manufacturer and ongoing communication between the manufacturer and customer will assure that strict guidelines are followed for assembly and enable additional, direct system recommendations or troubleshooting along the way, if needed.
Choosing a manufacturer that offers a complete cable carrier system provides the option of leaving the selection process up to the vendor with extensive experience, backed by valuable knowledge gathered from a wide range of field applications and laboratory tests. Most cable carrier manufacturers offer a range of sizes and types of product. Those with the largest, most comprehensive selection will still find it easier to specify a carrier system for the customer, given a few key application parameters. Since the vendor knows the full range of products available best, the customer is saved from wading through a large catalog and spending time going through information which may not be relevant to a particular application.
It is always worthwhile to choose a cable carrier manufacturer which continues to offer new products on a frequent basis. These products usually develop out of customer requests and fulfill a need not previously addressed. This also means finding a cable carrier system to meet your specific needs is virtually assured.
Continuous innovation combined with the system approach also affects technical sales staff knowledge. The technical salesmen who work with a company that stresses new products and quote cable carrier systems will be more aware of the most relevant, creative options, not only in carriers, but in cables, connectors and accessories as well.
Flexibility of the cable carrier vendor is also important. Look for those that offer multiple options for cable and hose accessibility (snap-open, zipper or push-through crossbars and snap-open lids on carriers), a variety of conduit strain relief and mounting options, a generous size selection within each product line, different price point options for the same application (with a comprehensive explanation if one system is recommended over another), and various service options.
And finally, a guarantee of quality backed by a full warranty is always a good idea for selection assurance. Look for a cable carrier manufacturer that offers both. By going with a cable carrier system, the customer is given a guarantee on all parts made by that manufacturer and all work done on all aspects of the system (carrier assembly, conduit installation and separation, termination, etc.).
|If you want to contribute a technical paper, please send a hard copy and IBMelectronic format (.txt file, .jpg file, or .gif file only). For more information, e-mail firstname.lastname@example.org.