概述

The simplest captivated screw is very similar to a regular screw with two specific features. The threads at the tip have an outer diameter greater than the unthreaded length between the head and the tip, while a flat step that is slightly larger than the thread diameter is fashioned on the underside of the head. While this is designed to retain itself in a panel by deforming it, the step on the head can be traded for a self-clinching retainer with a thin thread that accepts the screw. The design assumes the use of a tool in application and can accept a drive like a flathead or Philips head screwdriver.

应用

Given that an application for a screw with no retainer was discussed in the captivated screws section, here let’s consider the flare-mounted retainer. In some larger scale datacom applications, maximizing density is preferable for space efficiency. Mounting hardware for a cover plate might be as close to the edges of the panel as possible. This allows more room for internal components but limits the amount of material available to deform. A flare-mounted retainer allows for a captivated screw to attach closely and securely to the edge of the panel without unwanted deformation.

Cross-section schematic showing how a clinch bolt can retain itself in a panel or be retained by a self-clinching retainer with collapsible features
A flare-mounted panel fastener can be installed much closer to the edge of a panel
A self-clinching panel fastener may cause blowout when installed too close to a panel's edge
When tasked with maximizing the use of space, flare-mounted panel fasteners can mount screws
close to the edges of a cover plate without damaging the panel.

替代方案

Since flare mounted retainers rely on deforming the retainer against the panel, the hole in the panel requires a Countersink on the bottom side to accommodate moving material. This introduces an additional step in the manufacturing process. A self-clinching retainer doesn’t require this step and has the additional benefit of no protrusion on the opposite side of the panel from a flared shank, allowing for a tighter joint between surfaces. However, due to the deformation of a panel required to fill the clinching undercut, the hole needs to be further from the edge to avoid buckling the panel. The hardware for the mating thread that accepts the screw will then further encroach on the internals of the server housing.

常见的连接技术

While retainers can utilize any of the available attachment technologies based on the application, captivated screws without a retainer might fit best within the self-clinching category. Requiring a metal panel of a minimum thickness, the step on the underside of the head deforms the panel inwards so the threads prevent the screw from falling out.

PEM相关产品:

See size and material options for simple screws in our Product Finder:

To learn more, visit the PF Datasheet for simple captivated screws.

想要查找产品?
来试一试我们的新产品搜索工具吧!

有项目在手?

我们开始吧

请与我们谈谈定制零件、工具或工艺的相关事内容,我们有能力和资源来帮助您处理并攻克最难的工程挑战。

请与我们谈谈定制零件、工具或工艺的相关事内容,我们有能力和资源来帮助您处理并攻克最难的工程挑战。

查看工程指南

lady-1

有疑虑?

请与我们的工程师聊一聊

寻找可行的方案

现在就联系PEM®工程专家,为您极具挑战的应用找到可靠且成本效益高的紧固解决方案

或致电: 1-800-342-5736

搜索全站

您想找什么?

您可以用多种方式来搜索想要的内容,如通过完整的或部分料号来搜索库存或产品规格。 您也无需输入“库存“或“产品规格”。如何搜索:
完整或部分料号: “S-632-1ZI”, “CLS 632”
类型: “CLS”, “FH”, “SO”网站内容: “自扣紧螺母” or “PEM螺钉”