<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED>
<MULTIPLIER> 1,000

<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             JAN-01-1997             JAN-01-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997
<CASH>                                           4,092                   2,014                   2,119
<SECURITIES>                                        77                      78                      19
<RECEIVABLES>                                   31,684                  34,396                  37,509
<ALLOWANCES>                                     3,194                   3,086                   3,059
<INVENTORY>                                     52,034                  59,177                  62,080
<CURRENT-ASSETS>                                99,759                 109,640                 112,806
<PP&E>                                         241,981                 268,246                 277,788
<DEPRECIATION>                                  96,564                  99,347                  99,171
<TOTAL-ASSETS>                                 262,182                 295,816                 309,842
<CURRENT-LIABILITIES>                           59,092                  58,663                  41,409
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                        57,282                  57,776                  61,452
<OTHER-SE>                                      92,046                 103,088                 110,375
<TOTAL-LIABILITY-AND-EQUITY>                   262,182                 295,816                 309,842
<SALES>                                         77,026                 156,233                 234,666
<TOTAL-REVENUES>                                77,127                 157,384                 236,470
<CGS>                                           61,145                 119,543                 181,356
<TOTAL-COSTS>                                    4,376                   8,202                  12,250
<OTHER-EXPENSES>                                 (262)                   (229)                   (300)
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                                 144                     304                     707
<INCOME-PRETAX>                                 11,766                  29,662                  42,600
<INCOME-TAX>                                     3,883                   9,790                  13,853
<INCOME-CONTINUING>                              7,883                  19,872                  28,747
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                     7,883                  19,872                  28,747
<EPS-PRIMARY>                                      .29                     .72                    1.04
<EPS-DILUTED>                                      .28                     .70                    1.01


</TABLE>