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Any sourcing job has a few general criteria to watch for, regardless of component type. Some of them are obvious, others not so much:

• Quality 
• Availability 
• Application fit 
• Standards and regulations 
• Warranty and support 
• Cost 

Quality

This is the one your engineering team will care most about. Bad actors can cause:

• Circuit failure
• Poor performance of assembly
• Damage to equipment
• Danger to humans

Part quality problems most often come from:

• Bad batches: Variations in the manufacturing process can lead to inconsistencies across production runs. A poor-quality batch could result in circuit instability or shoddy performance.

• Counterfeits: The internet is a sea of low-cost fake parts that often compromise on quality. Accidentally ordering these imposters can lead to circuit failures and safety hazards.

• Obsolescence: Discontinued parts don't magically disappear the moment the manufacturer ends last-time buys. Using outdated components still on the market can render your design obsolete, affecting the performance and useful life of your product.

Availability

The waiting game isn’t fun, and it’s easy to lose.

Make sure the electronic components you’ve honed in on are available in the necessary quantities. Sometimes small-order lead times are short. Don't assume you'll get the same speed when you make a bigger order, even if it's the same part and manufacturer.

Order early and often if the parts are:

• Obscure
• In-demand
• Heading toward obsolescence

This approach makes replacements and expansions straightforward, limiting downtime and costly redesigns.

Another, more design-focused approach to shortages is substituting in an alternative part that offers similar functionality. You certainly shouldn’t throw safety or quality out the window, but settling for “close enough” might get your project out the door months sooner.

Tip: If your components tend to play hard-to-get, enlist the services of a distributor. Unlike a single buyer, a distributor has an extensive supplier network and a constant finger on the pulse of market changes.

Application Fit

If you’re building equipment whose failure could cause the loss of human lives or million-dollar machinery, don’t instinctively buy the cheapest wire or circuit protector.

When picking components, think about where and how your team will use them. For example, the intense heat of industrial furnaces or the freezing conditions in transportation refrigeration call for parts that can thrive in the extreme. In an energy facility with nonstop vibration, the components need to be mechanically tough. 

It’s also important that any new components play nicely with your current system. Talking to product experts or using simulation tools to see how your choices might hold up can save you headaches and money later.

To sum it up: Match your investment to the level of electrical performance, flexibility, and size you need. The results will be more durability and less upkeep – for both the part and the assembly. 

Standards & Regulations

The importance of certifications and standards largely depends on your use case and industry. Chances are you already have some marching orders for compliance – we’re talking about electricity, after all.

Electronic component standards usually account for:

• Safety
• Reliability
• Durability

If your company isn’t comfortable with selecting compliant parts, talk to an experienced distributor. If you can’t trust the component to do its job, how can you trust the full assembly to do its job?

Warranty & Support

This concept isn’t much different from a commercial electronic product like an iPhone. A warranty should reflect the maker's confidence in its product's durability and performance.

An electronic component purchase with a good warranty offers more peace of mind than a bad warranty or none at all. When sourcing electronic parts, weigh the importance of the component vs. the manufacturer’s warranty:

• Length – Reduces risk of incurring additional costs for replacements or repairs
• Coverage – Some warranties may cover only parts, while others include labor and even replacement services
• Terms – May include limitations on usage, environment, or maintenance requirements

Don’t forget your needs after the parts arrive. If your own operation lacks experience with the type of parts you need, check out the maker’s level of tech support. In big projects, after-sale services can soften the integration’s impact on your schedule. Give bonus points to sellers with full training resources and a maintenance program.

Cost

We were sneaky and waited until the end to include this.

Why? Because you already know upper management wants you to find cost-efficient parts.

Goto Qingjian Electronics to know more.

Actually, there’s another reason: Too often, procurement specialists go for the cheapest component possible. This short-sighted strategy may introduce into your design:

• Counterfeit parts
• Low-quality parts
• Parts that aren’t the best fit for your application

All of these mistakes can result in having to reorder parts, rework designs, and redo the production stage. These “re-”s in turn lead to:

• Downtime
• Delayed launch
• Extra testing
• Poor reputation with customers

If that happens, guess what your short-term “savings” got you? More long-term cost.

Thinking long-term means accounting for all factors of purchase cost:

Cable ties are simple fastening devices, typically made from plastic. They’re not structural and don’t provide a pathway for cabling. However, industrial cable ties can still maintain a semblance of neatness in the right setup, especially temporary ones.

Cable wraps are flexible sleeves made from fabric, neoprene, or Velcro. As you’ve probably figured out, they wrap around cables to keep them organized. They’re often lumped together with cable ties because both options are quick-and-easy solutions that don’t offer much physical support. The main difference is that you can adjust a protective sleeve without destroying it.

Cable trays are open, rigid structures that support and hold cables in place. Despite being a structural component, trays don’t fully enclose and protect the wires inside them. Industrial cable trays are only usable with certain cable types, per Article 392 of the National Electric Code.

Cable ducts are enclosed tubes with a removable cover so you can lay cable inside along the pathway. Ducts can consist of metal or plastic and often feature a segmented design.

Cable raceways look and function similarly to ducts, but they include an open channel or trough for accessibility. From there, you can leave the raceway covered or uncovered, opening it as necessary for changes. The extra usability comes at the cost of less protection.

Cable conduits are a specific type of tubing or enclosed channel made of metal or plastic. They can be either rigid or flexible. These products are where the buck stops if you need to comply with safety requirements.

Heat-shrink sleeve labels slip over the cable before termination. They allow users to slide them along wires or cables for optimal placement. Once you apply heat to affix the label, you’re stuck with that location. 

The heating process shrinks the sleeve to a predetermined size, typically 1/3 to 1/6 of its original diameter. For industrial labeling needs, it's crucial to select the appropriate diameter and type of sleeve. You can cut the length to size prior to heating.

Wrap-around labels are for use after termination. These labels are adhesive and wrap around the entire diameter of a wire. Available in preprinted and stand-alone forms, the material is typically clear polyester or vinyl, with a small, white area for marking by hand or printer. Special types of wrap-arounds are available for adding moisture protection, repurposability, or readability.

Flags can go on cables before termination to help ID them during installation, or after termination to provide permanent labeling. The material partially wraps around the cable and sticks to itself, forming a flag-like extension. This design is particularly useful for identifying cables in dense or hard-to-reach areas.

Tags also work either before or after the cable’s termination. The material makeup can be either plastic or metal. Tags’ main difference from cable flags is that you have to attach them with a tie or similar fastener. On the plus side, this makes them more durable for permanent labeling situations.

Overview of Fuses

Industrial fuses come in so many easy-to-find types that it’s common for two to look nearly identical. Problem is, they might function just differently enough to be dangerous. Worst-case scenario, this guessing game can lead to selecting the wrong fuse, putting people and expensive equipment at risk.

At least voltage rating is easy enough to nail down – all fuses are straight voltage-rated. A straight voltage rating means you can use the fuse in circuits with a nominal voltage up to its rated value between any two conductors. For example, an industrial fuse with a rating of 250 V is OK to use in a circuit where the line-to-neutral or line-to-line voltage is 250 V or less.

Overall, some buyers feel that fuses are simpler or more consistent sourcing options compared to mechanical overcurrent devices. If you’re not sure, ask a distributor with technical product expertise.

Interestingly, sizing an industrial fuse means taking both electrical and physical needs into account. The fuse’s voltage rating must comfortably exceed your application’s current level, or else it’ll blow needlessly. However, it must also fit inside the assembly without crowding other components, which could lead to heat buildup and other performance issues.

Start by calculating the maximum and minimum fuse ratings:

• Wattage / voltage = max fuse rating (amps)
• Max fuse rating * 1.25 = minimum fuse rating

Don’t use any so-called “10% rule.” Size the fuse for safety first, and keep the value well above the expected load. Balance this against the internal dimensions of the fuse’s intended home. Spec a fuse to a plausible maximum load to avoid overspending.

Finally, don’t forget to watch for these other factors when sourcing fuses:

• Current rating should be slightly above the circuit's normal current, but below the wire’s or device’s current capacity.
• Interrupt (breaking) capacity will need to be high if you’re working with a high-voltage application.
• A current-limiting fuse reduces the duration and magnitude of a fault current, minimizing equipment damage and protecting people.
• Corrosive & environmental threats are avoidable by picking a fuse with the right temperature rating, coating, fire rating, or build for your application.
• Speed comes in four tiers – ultra-rapid, fast-acting, time-delay, and dual-element – and should be selected based on how quickly you need circuit interruption.

Types of Fuses

Most buyers categorize fuses one of three ways: build, application, or operating characteristics. While it's tempting to go for the cheapest option in a given category, remember that a fuse is a safety device.

As you can see, sensor types are more application-dependent than your average electronic component. For example, pressure sensors are for measuring liquid and gas, while force sensors are for mechanical measurement. 

From there, pros and cons often vary by specific product. Some force sensors can measure in multiple directions. Along those lines, some flow sensors can measure flow direction as well as rate, but their performance can drop if there’s particulate matter in the fluid. And certain types of level sensors won’t work as well if there’s foam or vapor present above the liquid.

In the world of temperature sensors, many types are available (i.e. thermocouples, RTDs, thermistors) to suit different accuracy and range needs. Advanced models of vibration detectors can differentiate between normal vibrations and those signaling potential failures. And high-end motion and proximity sensors can tell the difference between human and non-human movement.

Some level sensors offer contactless measurement, reducing wear and contamination risks. In the pressure sensor market, some come with protective measures so that overpressure isn’t a risk.

Of course, all industrial sensors must provide some level of ability to work in rugged environments without losing accuracy. Regardless of purpose, industrial sensors typically require regular calibration, so don’t fret if that’s the case.

Overview of Terminal Blocks

Terminal blocks are the professional’s alternative to soldering or taping, offering a convenient way to connect and terminate wires.

The most popular mounting solution for terminals is a DIN rail. This tends to simplify wiring setup and save space in the enclosure.

Along those lines, accessibility is an important feature in terminal block installations. In addition to keeping terminal footprint minimal, consider using screws as your fastening method. These connections are easier to modify and add an element of futureproofing to your assembly.

Besides the usual comparison points, a common way to start your terminal block hunt is to check how many circuits the assembly needs. This determines the number of poles the block must have.

(Tip: With terminal blocks, it’s entirely possible your engineering team will care about only one criteria: compatibility. Many prefer that all terminal blocks in an installation come from the same manufacturer.)

Types of Terminal Blocks

There are many ways to classify industrial terminal blocks:

• Connection method
• Wire-securing method
• By function

Let’s focus on the most common way – connection method. You can learn about the other categories at the button further below.

Barrier strips (aka single-row) terminal blocks are extremely common in the U.S. They consist of three main parts: a plastic or thermoplastic body, multiple terminals, and barriers separating them. A screw or clamp connects the wires, and sometimes a small enclosure or lid protects them.

IEC PCB mount (aka Euro style or wire-to-board) terminal blocks are a staple of, you guessed it, PCBs (printed circuit boards). They work by placing bare wires in the module, where housing and a clamp secures the strands. PCB terminal blocks can be single-, dual-, or multilevel (usually three or four) structures. You can mount PCB blocks either through the board or via pluggable pin strip mounting.

Feed-through terminal blocks feature two input sides (one on each side), where two distinct wires are fed through the housing. They use the screw-in method of connection, coming with predrilled holes. They come in single, dual, or multilevel modules.

Edge connector terminal blocks accept a circuit board edge into their housing. Putting them together matches the copper traces and screws the block into an enclosure. This means the block only needs one discrete female connector.

By understanding how each type works, you can ensure safe connections, make maintenance and troubleshooting easier, and streamline the overall assembly.

Manufacturer Resources for Your Electronics Supply Network

Need to know where to buy electronic components safely and swiftly in today’s ultracompetitive market? 

As you window-shop, stay sharp for signals of whether the manufacturer’s size actually equates to quality.

In some ways, identifying the top component manufacturer comes down to your application’s specifics and level of complexity. Will the component be responsible for operating a 10-ton lift over workers’ heads? Will it provide data feedback from a commercial airplane? In mission-critical work, a brand you trust is worth its weight in copper

(Tip: In some assemblies, your engineers may prefer that all of a certain component [i.e. terminal blocks] come from the same manufacturer. It’s a compatibility thing.)

If it’s too close to call between two candidates, go with the company that’s got history on its side. A proven, financially stable operation is less likely to leave you holding a faulty batch with nobody to answer for it.

There are many good electronics manufacturers out there beyond the few highlighted for each component above. For a fuller list, see our supplier page:

Contact us to discuss your requirements of PCB Assembly services for rail transportation. Our experienced sales team can help you identify the options that best suit your needs.