TWELFTH WEEK

Twelfth week

  

Today January 8th, 2020, our classes got started. From the first hours our professor of technical drawing course has taught us some topics linked to geometrical tolerances. 
The importance that topic has at the moment of designing and manufacturing a piece of equipment. We have a new challenge for this month, and geometrical and dimensional tolerances will be used fully to achieve good outcomes.
Within major geometrical tolerances we have:

A) Form tolerances:

I. Straightness The axis of the cylinder, to which the tolerance frame is connected, shall be contained in a cylindrical zone of diameter 0.08.

II. Flatness The surface shall be contained between two parallel planes 0.008 apart.

III. Circularity The circumference of each cross-section shall be contained between two co-planar concentric circles 0.1 apart.

IV. Cylindricity The consider surface shall be contained between two coaxial cylinders 0.1 apart.

V. Profile of any line In each section parallel to the plane of projection, the considered profile shall be contained between two lines enveloping circles of diameter 0.04, the centres of which are situated on a line having the true geometrical profile.

VI. Profile of any surface The considered surface shall be contained between two surfaces enveloping spheres of diameter 0.02, the centres of which are situated on a surface having the true geometrical form.

B) Orientation tolerances:

I. Parallelism The toleranced axis shall be contained in a cylindrical zone of diameter 0.03, parallel to the datum axis A (datum line).

II. Perpendicularity The axis of the cylinder, to which the tolarence frame is connected, shall be contained between two parallel planes 0.1 apart, perpendicular to the datum surface.

III. Angularity The axis of the hole shall be contained between two parallel planes 0.08, apart which are inclined at 60 degrees to the surface A (datum surface).

C) Location tolerances

I. Position The axis of the hole shall be contained within a cylindrical zone of diameter 0.08, the axis of which is in the theorically exact position of the considered line, with reference to the surface A and B (datum planes).

II. Coaxiality The axis of the cylinder, to which the tolerance frame is connected, shall be contained in a cylindrical zone of diameter 0.08 coaxial with the datum axis A-B.

III. Symmetry The median plane of the slot shall be contained between two parallel planes, which are 0.08 apart and symmetrically disposed about the median plane with respect to the datum feature A.

D) Run-out tolerances

I. Circular run-out The radial run-out shall not be greater than 0.1 in any plane of measurement during one revolution about the datum axis A-B.

II. Total run-out The total radial run-out shall not be greater than 0.1 at any point on the specified surface during several revolitions about the datum axis A-B, and with relative axial movement between part and measuring instrument. The movement shall be guided along a line having a theorically perfect form of the contour and being in correct position to the datum axis.

After that day, we started with the second erronka. Basically, it´s about designing a melting base for our die. The teachers explained the RA´s of the challenge, and we solved the possible doubts.
The base has two main functions: attach the die to the press and dislodge scrap metal.

Here you can see a sample of a base, it is done by a student of Maristak Durango, the last year.

We have to deliver a file to Nagore, answering 16 questions about melting.