“Do unto others as you would have done unto you.” This phrase is known as the golden rule, and for good reason. It’s a broadly applicable guideline for behavior, based on the fundamental recognition that other people are the same as we are. This rule is particularly important in instances where there is a high price to be paid for failing to adhere to this simple tenet. One such instance is the manufacture of implantable medical devices.

In this industry, it’s necessary to ensure that each and every implantable device is created to the highest possible standards for safety and utility. The right tools must be chosen in their construction, the right process must be followed, and the quality of each product must be double-checked against internal and external standards. Why? To make sure nobody has a medical device implanted in them that you wouldn’t trust to implant in yourself. And one important way of accomplishing this goal is to select torque tools which can consistently deliver the high level of control needed for medical device manufacturing.

The Importance of Torque Control in Implantable Medical Devices

Few production applications have higher stakes and tighter requirements than the manufacture of implantable medical devices. Unsurprisingly, the manufacture of internal medical devices is also one of the most highly regulated assembly processes under U.S. law. As such, there are two primary considerations to take into account when creating these devices. First, the tools used must be capable of making adjustments within the fine limits of the product’s tolerances. Second, each aspect of the production process must be accomplished within the standards imposed by the U.S. Food & Drug Administration. Adherence to these standards must be documented so it may be proved upon request.

To select the appropriate tools for implantable medical device manufacturing, it’s necessary to understand the importance of torque control. Torque is the amount of turning or twisting force exerted on a fastener in order to bring that fastener to the level of tension it needs to maintain its position. If an insufficient amount of torque is applied to a fastener, the fastener will not have enough tension to remain in place. Whether gradually over time or as a result of a shock or jar, that fastener may come loose, allowing the materials it was holding to come apart.

Conversely, if too much torque is applied to a fastener, it will suffer from a surfeit of tension. This excess tension may cause the fastener or the materials it is holding together to warp or otherwise deform. As a result, fasteners or their substrates may fail. In any product, when one fastener fails, all other fasteners are subjected to an increased level of stress, potentially causing them to fail as well. This is known as a cascading failure and is something you obviously want to avoid.

Either scenario is further complicated when a product is implanted in a living patient. If a fastener comes loose, it does so inside a person. This highly undesirable situation may result in injuries, such as internal bleeding or infection, as well as attendant complications. If an implanted device fails, the patient will lose the functionality it provided or augmented, and they may experience pain or lack of mobility. If the patient is dependent on the device for a critical bodily function, such as circulatory or respiratory activity, the consequences of failure could be life-threatening.

Lastly, if surgery was required to implant the device in the first place, then surgery may be required to remove, repair, or replace it. All of this is best avoided, both for the sake of the patient and the sake of the manufacturer’s business. After all, any failure can expose the manufacturer to severe liability, and repeated failures may cause reputational damage, legal sanction, and the loss of business.

Ensuring Compliance when Manufacturing Implantable Medical Devices

Each medical device comes with its own set of guidelines for manufacturing. Some require premarketing approval by the FDA. Because approval of a manufacturing process, including the tools selected, can take many years, it’s important to be sure your process will meet guidelines before you invest significant capital. If you intend to manufacture a novel device, the approval process will likely be even more stringent.

To determine the regulatory requirements which govern the production of a given device, consult Title 21 of the Code of Federal Regulations, parts 868-892. This section of the federal code has been separated by the intended usage of the device, with anesthesiology devices listed in parts 868-869, cardiovascular devices listed beginning in part 870, etcetera. To facilitate timely information retrieval, the FDA has created a searchable database for medical devices. The extant list can be downloaded at any time and is updated regularly, every Sunday. At the time this article was written, 608 implantable medical devices were listed in the database. Consulting and adhering to the FDA guidelines for each product you intend to manufacture will help ensure you build a safe, functional product. It will also reduce your exposure to liability associated with your device.

Selecting Appropriate Torque Tools for Medical Device Manufacturer

It’s critical to choose manufacturing tools which can deliver the correct amounts of torque to the fasteners holding implantable medical devices together. These tools must be able to accomplish two things: delivering torque on the scale of a device’s tolerances and mechanically limiting the amount of torque delivered.

For the most part, implantable medical devices are small objects, held together by small fasteners. The amount of torque it takes to hold these fasteners in place will likely be measured in inch-ounces or the lower ranges of inch-pounds, as opposed to grosser scales, such as pound-feet. For help converting torque measurements, use this calculator. The exact requirements for a given device’s fasteners will be provided by the device’s designer or engineer. They will have been developed using published information on similar fasteners as a reference and finalized only after comprehensive product testing.

Both hand and electric torque tools are capable of making adjustments within this range. The next step is to find tools which can consistently prevent over-torque conditions. Electric tools must have built-in clutch mechanisms or other safeguards to prevent them from delivering too much torque. Hand tools, whether their torque limits are internally or externally adjustable, must likewise have a clutch mechanism that disengages when the appropriate torque has been reached. Tools without torque limits should be avoided.

Internally adjustable hand tools are more secure than externally adjustable tools, as they are less likely to be accidentally set to the wrong torque value. Externally adjustable tools may still be useful, however, if the device requires many fasteners, each with different torque standards.

Although hand tools can be useful, electric tools are likely to be superior for a number of reasons:

Speed:

Electric tools are simply faster than hand tools. Their implementation will allow a company to create more devices in the same amount of time. This advantage is widened even further with the introduction of automated electric tools.

Oversight:

Electric tools can be augmented by screw counters or DC control systems, which will automatically detect omissions, unfinished rundowns, cross-threading, and other errors. These systems will alert supervisors and prevent the product from continuing to the next stage in manufacturing.

Documentation:

The oversight provided by screw counters or DC control systems automatically generates a paper trail recording each fastener installed in the product. This allows internal and external auditors to easily review a detailed production history. As the adage goes, if it wasn’t documented, it didn’t happen.

Reaction Stability:

Electric tools can be stabilized with mounted torque arms. These torque arms prevent any torque from accidentally being absorbed by a human operator, resulting in a more accurate delivery of precise amounts of torque.

In addition, special requirements may dictate the selection of certain tools. If using fasteners made of softer materials, such as plastic, it may be necessary to choose an electric screwdriver capable of making soft stops to prevent product damage. If the device being manufactured requires clean room conditions, then tools must be chosen which are rated for use in that level of clean room. If the product has sensitive electronic components, then a tool built to prevent electrostatic discharge should be selected.

Calibrating Torque Tools to Meet Manufacturing Demands

In order to deliver the precise amounts of torque you need, your tools must be accurately calibrated. Torque tools will eventually slip out of calibration over time, or they may be accidentally broken or damaged. As any resulting deviation in torque control can have serious ramifications, tools must be tested regularly to ensure they are in good working order. The typical calibration testing interval is six months. However, with high-risk applications like the manufacture of implantable medical devices, this period may be shortened to monthly, weekly, or even daily.

A calibration check can be as simple as inserting the tool in question into a torque tester for a pass/fail inspection. Should the tool fail, it must be flagged and removed from service until it is recalibrated. Tools which have failed a calibration check should be checked twice as often after they have been returned to proper calibration.

Tools can either be calibrated in-house using specialty equipment or shipped to a certified service center for professional calibration. Both in-house calibration procedures and service centers must be certified under National Institute of Standards and Technology or International Organization for Standardization standards. Not only should the tools themselves be calibrated, but the equipment used to calibrate them must be tested and certified as well. In every case, what is calibrated must also be documented.

Choosing the right torque tools for the manufacture of internal medical devices must be done carefully, with an eye towards safety, compliance, and efficiency. The correct choice depends on the exact requirements of the device that is being assembled. No matter what the exact specifications of the product are, attention to detail in selecting torque tools is essential to preventing accidents and limiting liability.

At Mountz Inc., we understand the importance of proper tooling for the success of your company. For over half a century, we’ve been making trustworthy tools for low-tolerance applications. Just as people rely on your products for their livelihoods, you can rely on our tools for yours. To see our line of products, download our catalog. To inquire about price, request a quote. If you have any questions, ask one of our experts. If you’d like a product demonstration, request an appointment.