TCustomBarSeries.BarWidthPercentproperty BarWidthPercent: Integer;
Default Value: 70
The BarWidthPercent property determines the percent of total Bar width used. Setting BarWidthPercent := 100 makes joined Bars. You can control how many Bars appear at same time by using TChart.MaxPointsPerPage property. The BarWidth and BarHeight properties indicate Bar dimensions in pixels.