For table cells the ‘width’ property should be used, as the ‘min-width’ and ‘max-width’ is undefined for table cells. See the specification:
“In CSS 2.1, the effect of ‘min-width’ and ‘max-width’ on tables, inline tables, table cells, table columns, and column groups is undefined.”
To enforce the width, you may try to change the table-layout property to “fixed”. The specification describes the algorithm pretty clearly.