$sql="INSERT INTO test (partnum, partname, shelf, bin, instock, order, machine)
VALUES
('$_POST[partnum]','$_POST[partname]','$_POST[shelf]','$_POST[bin]','$_POST[instock]','$_POST[order]','$_POST[machine]')";
try changing to:
$sql="INSERT INTO test (partnum, partname, shelf, bin, instock, order, machine)
VALUES
('{$_POST['partnum']}','{$_POST['partname']}','{$_POST['shelf']}','{$_POST['bin']}','{$_POST['instock']}','{$_POST['order']}','{$_POST['machine']}')";