Weekly Update - Rivets and Molds

Hello, blog Readers!

Today, we will provide you data about this seventh week in the Integrator's Project acquired progression.

In an internal meeting of the Solarium Engineering Team, it was discussed the cast for the rivet creation. It will be used the ABNT SAE 1020 steel for the casting, where the brass will be poured. However, a concern about the thermal dilation in the cooling period was present, since it could generate deformations and therefore compromising the final product. However, as the iron-carbon alloy will be at normal temperature conditions and the brass overheated, there will be present a temperature differential corresponding to heat. This transfer brings on the dilation of the first and volumetric reduction of the second [alloy], then causing an spacial ease in the melted brass occupation. During the cooling period, then, it was concluded that there would be no internal stresses in the final system.

Still considering the refrigeration period, an phenomena called "shrinkage" (rechupe, in portuguese) occurs. It consists in the volumetric contraction of a molten metal during its solidification, generating a smaller solid volume than the original liquid [volume]. For the melted rivet doesn't possess a smaller volume than computed, it is considered the application of a "massalote" (molten metal feeder that cools slower). The security factor, determined as 3 by the Team, compensates some bogus parameters of the molten material. Therefore, an excess of the material guarantees no losses in the result.

This week, it was analysed, reviewed and delivered the Cast and Brass Rivets Fabrication Project's Report. Accordingly to Garcia (2007), "the total volumetric contraction consists in the fraction between the final liquid and solid volumes". Computing those contractions, it was possible to find the shrinkage volume, accordingly to Picture 1.

Picture 1. Screen capture representing the shrinkage volume calculation, considering the volumetric contraction data. The software MathCad Prime 3.1 was used for this.
Source: own.

With the shrinkage height and rivet length, the last's height was computed with the Equation XX demonstrated in the Picture 2. As written before, the security factor was involve in this calculus.

Picture 2. Screen capture representing the shrinkage and total height's calculation. The software MathCad Prime 3.1 was used.
Source: own.

It was settled that the rivet would have a bigger volume, when created, so the second head could be forged by the Team. Therefore, the final rivet would be ready for the stress.

Picture 3. Internal cast drawing, with rivet positioning.
Source: own.

We hope this had been informative for you!

Best regards,
Solarium Engineering Team