1. There is appearance of the dimples during AJM.
a) True
b) False
Explanation: Appearance of the dimples during AJM for 10s. for various machining sets of abrasives and ceramic materials. Properties of the dimples do not differ in terms of the removed volume, but also the roughness of the struck face for different combination of abrasive particles and workpiece material.
2. In AJMM, the substrate has to be shielded by a mask.
a) True
b) False
Explanation: In AJMM, the substrate has to be shielded by a wear resistant mask that is patterned with the desired contour. The mask determines the accuracy of the dimensions in the plane of the desired structure.
3. During blasting, the workpiece is exposed to an abrasive air jet pressure of _____ MPa.
a) 0—1
b) 0—0.2
c) 0.2—0.8
d) >1
Explanation: During blasting, the workpiece is exposed to an abrasive air jet pressure of 0.2-0.8 MPa and abrasive particles average diameter of 10-100 μm. The scan strategy and the particle beam profile of the nozzle are of great importance.
4. Performance of the AJMM process is dependent on the quality of the mask
a) True
b) False
Explanation: The quality of the mask influences the performance of AJMM. The main qualification for a good mask material is a low erosion rate. It also requires the capability of an accurate and easy pattern transfer, and the ability to retain the irresistance in discontinuous layers.
5. How many types of materials can be used during AJMM?
a) 1
b) 3
c) 8
d) there is no compulsion on the material
Explanation: Three groups of mask materials can be applied to AJMM:
• Ductile materials such as metals.
• Elastic materials such as elastomer sand.
• Photo-resists as used in IC-industry.
6. The usability of the mask is affected by imaging accuracy.
a) True
b) False
Explanation: Each material used for making mask, needs a sufficient erosion resistance related to the substrate especially at normal blast angles. Furthermore, the achievable imaging accuracy determines the usability of a mask and minimum achievable features size.
7. To apply metal mask plate for AJMM, magnetic clamps are used.
a) True
b) False
Explanation: Metals having low erosion rates are suitable for making masks for AJMM. To apply metal mask plate for AJMM, it can be magnetically clamped directly to the target or by introducing an intermediate protection/ adhesion layer.
8. Which of the following have a low erosion rate?
a) Ductile materials
b) Malleable materials
c) Hardened materials
d) Low melting point materials
Explanation: Ductile materials, like metals, have a low erosion rate, especially at perpendicular impact. This makes them suitable to be used as a mask material. It can be used by means of a thin plate (e.g. stainless-steel).
9. Limitations in feature size are the major drawback of the metal masks.
a) True
b) False
Explanation: The disadvantages of this mask type are the limitations in feature size (approximately 50 μm) and pattern constraints (circular patterns cannot be used because the inner side should be supported).
10. Behaviour of elastomer materials is dependent on temperature.
a) True
b) False
Explanation: In contrast to ductile or brittle materials, elastomers behaviour is dependent on temperature, rate of deformation and particle velocity. Thus elastomers can show ductile, elastic and brittle behaviour.