Burrs are usually formed on external corners of the powder compacted components as a natural part of the process, the reason being that there has to be a little play between the die, punches and core to allow for their movement relative to each other during compaction and to allow for variations in the thermal expansion of the various tool parts.
The handling of components, subsequent processes or even the deburring process itself can wear away the burrs, break them off or bend them, thus resulting in yet another type of defective corner.
Therefore, it is necessary to define what is acceptable rather than use the general expression "burr-free" and "sharp-edged".
The permissible condition of corners should be defined in a way which states a tolerance for what is acceptable, e.g. through the application of ISO 13715 or DIN 6784.
However, this does not mean that burrs have to be accepted under all circumstances. There are methods for removing burrs or at least reducing their size, or alternative methods for concealing them relative to the functional surfaces.
The first and, as a rule, most economical method is a change in construction.
If a sharp corner is chamfered instead, there will still be a burr but if this is less than the depth of the chamfer this may no longer interfere with the functioning of the component.
Alternatively the burr can be reduced or perhaps removed entirely through the mechanical effects of vibration deburring, brushing or e.g. glass blasting. It is important to stress that these methods have their limitations, e.g. only those corners which are fully exposed to the mechanical impact will be deburred, and consequently such methods cannot be used to obtain complete deburring.
Finally, burrs may be entirely removed through thermal deburring or electrochemically. However, this is generally not recommended as this is extremely expensive as a rule.