In the world of plastic staking, there are several different technologies to choose from. Common technologies include ultrasonic, thermal punch, hot air cold punch, and of course Extol’s InfraStake. Each of these technologies is appropriate for use in different situations, but today I’d like to spend some time discussing three applications where InfraStake is the best method for the job.
When a tightly staked assembly is critical
We’ve all been there, you’re driving down the road and you hear it...a faint rattling coming from somewhere in your car. You’re not quite sure where it’s coming from, but you are certain that it is driving you to insanity as you frantically begin to elbow and slap various interior trim pieces in an attempt to pacify the source of your irritation before you lose your mind. No one wants to be subjected to this kind of torture; therefore in situations where your staked bosses must be tight to avoid unwanted rattling (or noise, vibration, and harshness as many in the industry call it), it is critical that you achieve a tight stake. To do this, most staking technologies require auxiliary clamps around the part nesting to be used to hold the parts together. However, if those clamps are not close enough to the boss location it is possible for small gaps to still be present under the staked boss. InfraStake, on the other hand, has clamping built right into the module and therefore clamps right around the boss. This ensures a nice, tight stake every time.
When you need a low-impact staking method that won’t damage your parts
Common staking methods like thermal punch or hot air cold stake introduce a significant amount of heat to an assembly, not just to the boss, but to the components around the boss as well. This can be a big problem if there are heat sensitive materials nearby such as the solder on circuit boards, thin paper, fabric, vinyl, or rubber. In contrast, the InfraStake process uses infrared energy that is focused only on the boss and is contained within the concentrator at the end of the module. This way, nothing outside of the concentrator is affected by the heat. Not only does this mean that your heat sensitive materials stay safe, it also keeps your operators safe from potential burns as well.
Another common source of part damage during the staking process comes from vibration. The ultrasonic staking process uses rapid vibration to generate friction which heats the boss and allows it to be staked. However, this same vibration can also wreak havoc on the show-surface or A-surface of the part, causing marks and scratches. It can also loosen wired electrical connections. InfraStake has the advantage here because it uses precisely controlled infrared energy to heat the boss instead of friction so your A-surface and any sensitive connections will stay untouched.
When your staked boss needs to have a clean aesthetic
Common complaints of many staking processes include material sticking and stringing as well as excessive flash. Both of these issues can be a big deal if you want to stake on a surface that the end user may see or if you simply want your product to have an all-around clean look. Luckily, both of these issues can be avoided using the InfraStake process. Sticking and stringing generally occurs when the tool that forms the boss is hot and not properly cooled before retracting from the boss. This causes the semi-molten plastic to stick to the tool and produce unsightly stringing. With the InfraStake process, the punch tool that forms the shape of the boss is not heated and therefore it takes significantly less time for the plastic to resolidify after the heating cycle. By the time the punch retracts, the plastic is fully cooled and there is little risk of sticking or stringing. Flash, on the other hand, can be controlled both by correctly designing the punch tool to match the volume of the boss and also by controlling how fast the material is heated. Some materials, when they are heated too quickly, have a tendency to flow in an uncontrolled fashion. This can cause unsightly flash. InfraStake uses power levels during the heating process to apply just enough energy to bring the plastic to a moldable state without overheating the material.
While there are certainly other reasons for choosing InfraStake, the three listed above are some of the most commonly cited by our customers. Have you tried InfraStake? If so, what was your reason for using it?